TL;DR
Double-muscle cattle. Double-muscle mice. A double-muscle kid in NEJM. What's in the gray-market vial: probably not follistatin.
What is it? An endogenous glycoprotein that sequesters myostatin and activins, releasing the brake on muscle growth. FS-344 and FS-315 both cleave to the same active species in vivo.
What does it do? Binds myostatin and activins with high affinity. Rodents grow bigger muscles. Cardiac and tendon tissue lag, which is where injury risk shows up.
Does the evidence hold up? Pathway is ironclad (McPherron 1997, Schuelke 2004). Injectable protein is not. Every real human trial used AAV gene therapy (Mendell 2015 IBM; Al-Zaidy 2015 BMD). Recombinant follistatin-in-a-vial has zero controlled human data.
Who uses it? Bodybuilders and recomp chasers buying glycoprotein vials that few vendors can manufacture correctly.
Bottom line? Genetics nailed. Vial quality: flip of a coin.
What It Is
Follistatin (FST) is an endogenous single-chain glycoprotein, first characterized in the 1980s in ovarian follicular fluid, that acts as a high-affinity binding protein for members of the transforming growth factor-beta (TGF-β) superfamily — most notably myostatin (also known as growth differentiation factor 8, GDF-8), activin A, activin B, and several bone morphogenetic proteins. By sequestering these ligands and preventing their engagement with activin-receptor type II (ActRII) signaling, follistatin functions as the endogenous "brake release" on muscle protein synthesis, satellite cell proliferation, and a set of related reproductive and developmental programs.
The human follistatin gene (FST) generates two principal protein isoforms by alternative splicing: follistatin-288 (FS-288), which binds heparan sulfate proteoglycans on cell surfaces, and follistatin-315 (FS-315), which circulates free in plasma. Both are processed from a larger 344-amino-acid precursor (FS-344). "Follistatin-344" as sold in the research-peptide community usually refers to the full-length precursor; "Follistatin-315" refers to the dominant circulating form. In vivo, the precursor is cleaved and FS-315 and FS-288 are the functional species; the labeling on vendor products is often inconsistent with the actual isoform content.
The biological rationale for pharmacologic follistatin comes from genetic experiments that are among the most dramatic in modern muscle biology. Myostatin knockout mice (McPherron, Lee 1997; Nature) develop 2–3× normal muscle mass. Belgian Blue and Piedmontese cattle carry naturally occurring myostatin loss-of-function mutations and display the "double-muscled" phenotype familiar from agricultural breeding. Schuelke et al. 2004 (New England Journal of Medicine; PMID 15215484) documented a single German child with homozygous myostatin loss-of-function who displayed extraordinary muscularity from birth and could lift 3 kg dumbbells at extended arm at 4 years old. The pathway is unambiguously the dominant negative regulator of human muscle mass.
Translating this to therapy has been challenging. Recombinant follistatin protein is a relatively large, fragile glycoprotein that is difficult to manufacture at biological quality outside academic and industrial pharmaceutical settings, has uncharacterized plasma pharmacokinetics in humans, and carries potential immunogenicity. The clinically advanced programs have therefore pursued AAV-follistatin gene therapy — adeno-associated-virus-delivered follistatin expression cassettes — rather than recombinant protein. Mendell and colleagues at Nationwide Children's Hospital conducted Phase 1/2 AAV-follistatin trials in inclusion body myositis (Mendell 2015) and Becker muscular dystrophy (Al-Zaidy 2015), demonstrating safety, follistatin expression, and meaningful functional gains. Injectable recombinant follistatin for healthy community users occupies an entirely different category — no controlled human trial data, significant sourcing risk, and uncharacterized long-term safety.
Mechanism of Action
Follistatin's mechanism is ligand sequestration of TGF-β superfamily members, with myostatin as the central target for muscle-related effects.
- Myostatin (GDF-8) neutralization — Follistatin binds myostatin with high affinity, preventing myostatin from engaging activin receptor type IIB (ActRIIB) on muscle cells. Normally, myostatin-ActRIIB signaling activates Smad2/3 transcription factors that inhibit muscle protein synthesis and satellite cell activation. Blocking this signaling is the principal mechanism behind the hypertrophy phenotype.
- Activin A and activin B neutralization — Follistatin also binds activins, which signal through overlapping ActRII receptors and contribute to muscle-growth inhibition. Activin A additionally plays roles in reproduction (FSH regulation), hematopoiesis, and wound healing. Broader activin neutralization by FS-344 / FS-315 has been associated with reproductive and hematologic effects in preclinical models.
- Satellite cell activation — With myostatin inhibition, myogenic satellite cells proliferate and fuse more readily, supporting both muscle fiber hypertrophy (existing fiber growth) and, in animal models, hyperplasia (new fiber formation). Hyperplasia is rarely documented in humans.
- FS-315 vs FS-288 vs FS-344 distinction — FS-315 circulates as the dominant plasma form and has the broadest systemic activin- and myostatin-binding activity. FS-288 binds to heparan sulfate proteoglycans on muscle-cell surfaces, providing localized, muscle-biased myostatin neutralization with less systemic activin impact. FS-344 is the full-length precursor, processed in vivo. Community-marketed "FS-315 vs FS-344" distinctions are often more marketing than biology, since FS-344 is cleaved to the other isoforms upon exposure to physiologic proteases.
- Downstream signaling — With ActRII signaling relieved, the ubiquitin-proteasome muscle-proteolysis program (MuRF-1, atrogin-1) is downregulated, mTOR/Akt protein-synthesis signaling is indirectly facilitated, and satellite-cell MyoD/myogenin pathways are activated.
- Other TGF-β ligands — Follistatin binds several BMPs (BMP-2, BMP-6, BMP-7) with lower affinity than myostatin/activin. These interactions may contribute to bone and developmental effects.
- Cardiac and tendon tissue — Cardiac muscle is more susceptible to pathologic remodeling under chronic myostatin inhibition than is skeletal muscle — rodent studies have shown ventricular dysfunction with extreme myostatin blockade. Tendons, ligaments, and connective tissue do not grow proportionally to muscle, creating a theoretical injury risk from disproportionately large muscles on un-adapted tendons.
- Reproductive axis — Activin neutralization suppresses FSH secretion in the anterior pituitary (activin normally stimulates FSH). FS-344 with broader activin-binding activity is more likely to impact reproductive hormones than FS-288 with its localized muscle-surface action.
- What follistatin does not do — Does not directly stimulate muscle protein synthesis (it releases an inhibitor, rather than acting as a growth-signal agonist). Does not engage androgen, growth hormone, or IGF-1 signaling directly. Does not cross the blood-brain barrier meaningfully.
What the Research Shows
The follistatin / myostatin pathway is one of the best-validated muscle-biology targets. The evidence for exogenous follistatin as a therapeutic is much thinner, split across genetic validation, AAV gene therapy, and the essentially unvalidated recombinant-protein approach.
- Myostatin knockout mice (McPherron, Lee, Lee 1997; Nature) — Seminal demonstration of the pathway. Myostatin-null mice (Mstn−/−) display 2–3× normal muscle mass. The "double-muscle" phenotype.
- Belgian Blue and Piedmontese cattle — Naturally occurring myostatin-inactivating mutations. Classical double-muscle phenotype; an established farming example of the pathway.
- Schuelke et al. 2004 (NEJM; PMID 15215484) — Human case report of a child with homozygous myostatin loss-of-function showing extraordinary muscularity and strength. Gold-standard evidence that the pathway translates to humans. The child was reported to remain healthy in follow-up years after.
- Lee & McPherron 2001 (PNAS; PMID 11459930) — Regulation of myostatin activity and muscle growth via follistatin and related inhibitors. Established the pharmacologic rationale for follistatin-based myostatin inhibition.
- AAV-follistatin in inclusion body myositis (Mendell et al. 2015; PMID 25495607) — Phase 1/2 AAV1-FS344 gene therapy trial at Nationwide Children's Hospital. Participants received intramuscular AAV-follistatin-344 into quadriceps muscles. Follistatin expression was detected, safety was acceptable, and functional improvement on the 6-minute walk test was observed in a subset of participants.
- AAV-follistatin in Becker muscular dystrophy (Al-Zaidy et al. 2015; PMID 25738490 / Mol Ther 2015) — Similar AAV1-FS344 program in BMD. Again, follistatin expression detected, some functional improvement, acceptable safety over the reporting window.
- AAV-follistatin longer-term follow-up (Mendell et al. 2017, Mol Ther; PMID 28245993) — Extended follow-up of the inclusion body myositis gene therapy cohort. Sustained follistatin expression and functional outcomes at extended timepoints.
- Body composition in animal models — Exogenous follistatin administration in rodents produces dose-dependent lean mass gain and fat mass reduction. Cardiac effects at high doses are a documented concern.
- ActRIIB-Fc and myostatin antibodies (related class) — Programs targeting myostatin via soluble ActRIIB decoy receptors (e.g., bimagrumab) or monoclonal antibodies (domagrozumab, landogrozumab, stamulumab) have advanced further clinically than recombinant follistatin protein, with mixed Phase 2/3 outcomes — muscle mass gains reliably achieved; functional outcomes in dystrophies and aging have been less robust.
- Injectable recombinant follistatin in humans — Essentially no controlled human trial data. Any efficacy claim from community-sourced injectable follistatin rests entirely on anecdote.
Research Limitations — Strong Pathway Biology, Weak Protein-Drug Evidence
The myostatin / follistatin pathway is genetically and pharmacologically validated at the highest standard of evidence (knockout models, natural human mutations, multiple independent convergent pharmacologic programs). The case for injectable recombinant follistatin specifically is dramatically weaker — no controlled human trial, severe manufacturing complexity, uncharacterized pharmacokinetics, immunogenicity concerns, and widely variable research-peptide product quality. Gene-therapy programs are more advanced clinically than protein-injection approaches. Anyone using community-sourced injectable follistatin should recognize they are not "using the compound that worked in the Mendell trials" — those used AAV-delivered gene therapy, not recombinant protein.
Human Data
- Schuelke 2004 (NEJM) — single-case myostatin-null human — The only well-documented human case of inherited myostatin deficiency. Extraordinary muscularity, healthy through follow-up.
- Mendell 2015 — AAV-follistatin Phase 1/2 in inclusion body myositis — AAV1-FS344 intramuscular gene therapy; 6 IBM patients. Functional improvement in walk test in responders; follistatin expression confirmed.
- Al-Zaidy 2015 — AAV-follistatin Phase 1/2 in Becker muscular dystrophy — Same AAV1-FS344 approach in BMD. Similar findings.
- Mendell 2017 Mol Ther — long-term follow-up — Extended follow-up reporting sustained expression and safety.
- Nationwide Children's gene therapy program — Broader follistatin gene-therapy research base led by Brian Kaspar, Jerry Mendell, and colleagues. Has since pivoted some resources to other dystrophy targets.
- ActRIIB / anti-myostatin class trials (comparators, not follistatin) — Multiple sponsor programs (Novartis bimagrumab, Pfizer domagrozumab, Lilly landogrozumab, Wyeth stamulumab) tested myostatin-axis blockade in Duchenne muscular dystrophy, sporadic inclusion body myositis, hip fracture recovery, and sarcopenia. Muscle growth generally achieved; clinical endpoints less reliably met. Provides class-relevant safety and efficacy context.
- No controlled injectable-protein trials — No published RCT of recombinant follistatin protein in healthy humans or in any clinical indication.
Dosing from the Literature
There is no validated human dosing framework for recombinant follistatin. The doses below are community-circulated and not derived from controlled trials.
| Route / Context | Dose Range | Frequency | Notes |
|---|
| AAV-follistatin gene therapy (Mendell 2015) | 1.2 × 10¹⁰–6 × 10¹¹ vg/kg IM | Single injection | Gene therapy, not recombinant protein. Not replicable outside a trial setting. |
| Community FS-344 injectable protein | 100 mcg/day (typical reported) | Daily SubQ or IM, 10–30 day course | Not trial-validated. Anecdotal. |
| Community FS-315 injectable protein | 100 mcg/day (typical reported) | Daily SubQ or IM, 10–30 day course | Preferred in some community reports for muscle-specific effect with less broad activin binding. |
| Cycle duration | 10–30 days | — | Short cycles favored due to immunogenicity concern and cost. |
| Rest between cycles | Equal or longer than on-cycle | — | Allow any anti-drug antibody titers to decline. |
Dosing Disclaimer
Recombinant follistatin is not FDA-approved and has no clinical-trial-validated dose. Community doses (100 mcg/day typical) are derived from vendor recommendations and anecdote, not from dose-finding studies. Bioactivity of gray-market recombinant follistatin varies dramatically between vendors — purity, proper folding, glycosylation, and true protein content are all quality-control concerns that cannot be resolved without analytical verification (HPLC-MS minimum; ideally cell-based bioassay). Many community users are paying for material that has little or no bioactive follistatin content. Even if the product is bioactive, long-term safety, immunogenicity, and efficacy are unknown.
Reconstitution & Storage
Follistatin is supplied as lyophilized protein, typically in 1 mg vials. Unlike smaller peptides, follistatin is a full glycoprotein and requires careful reconstitution and handling to preserve structural integrity.
| Vial Size | BAC Water | Concentration | Per-Dose Volume (100 mcg) |
|---|
| 1 mg | 1 mL | 1 mg/mL | 0.1 mL (10 units on U-100 syringe) |
| 1 mg | 2 mL | 0.5 mg/mL | 0.2 mL (20 units) |
| 5 mg | 5 mL | 1 mg/mL | 0.1 mL (10 units) |
- Reconstitution — Add BAC water slowly down the vial wall. Do not shake. Glycoprotein structure is fragile; aggressive handling can denature it.
- Storage (lyophilized) — −20°C desiccated, dark. Protect from repeated freeze-thaw cycles.
- Storage (reconstituted) — 2–8°C refrigerated. Use within 7–14 days; reconstituted glycoproteins are less stable than smaller peptides.
- Injection sites — SubQ or IM. Some community protocols use intramuscular injection into the target muscle group, but this has no controlled-data basis and is distinct from the intramuscular AAV gene therapy injections.
- Inspection — Discard if cloudy, visible particulate, or markedly discolored.
- Do not use past BUD — Protein-drug stability is more time-sensitive than small-peptide stability.
→ Use the Kalios Dosing Calculator for follistatin scheduling
Side Effects & Risks
Important
Follistatin is a fragile glycoprotein few vendors manufacture correctly. WADA bans it under S2. Myostatin inhibition carries theoretical cardiac and cancer concerns, and immunogenicity in humans is unstudied. This is a doctor conversation, not a vial-and-syringe decision.
The follistatin / myostatin-inhibition class has theoretical and (from class programs) documented concerns that should weigh heavily for anyone considering unsupervised use.
- Immunogenicity — As a large glycoprotein, recombinant follistatin can trigger anti-drug antibody formation. Antibodies may neutralize efficacy over time and could, in rare cases, cross-react with endogenous follistatin — the most concerning theoretical scenario because endogenous follistatin has broad physiologic roles. No systematic human immunogenicity data for injectable follistatin exists.
- Cardiac remodeling (theoretical) — Chronic myostatin inhibition in rodent models can produce ventricular dysfunction. Cardiac muscle is more vulnerable than skeletal muscle to imbalanced remodeling under this axis. No follistatin-specific human cardiac outcomes data exist.
- Tendon and connective-tissue injury — Muscle can grow faster than the connective tissues attaching it to bone. Rapid myostatin inhibition without parallel tendon adaptation has been associated with tendon rupture in case reports from the broader strength-enhancement community. Prudence: gradual training loads, long warm-ups, avoid max-load testing during cycles.
- Reproductive effects — Activin A plays a central role in pituitary FSH regulation. FS-344's broader activin-binding activity can (theoretically and in preclinical models) alter FSH, LH, and downstream reproductive hormone signaling. FS-315 with narrower activity has less documented reproductive impact. Monitor reproductive hormones.
- Hematologic effects — Activin A is involved in erythropoiesis and hematopoietic stem-cell maintenance. Chronic broad activin inhibition could theoretically affect blood cell production. Limited human data.
- Muscle growth overshoot — Unchecked hypertrophy can produce cosmetic asymmetry, muscular imbalance, and postural strain if the pharmacology interacts poorly with the training stimulus.
- Metabolic effects — Acute muscle anabolism can increase caloric requirements, alter insulin sensitivity, and in some community reports produce hypoglycemic tendencies.
- Long-term safety unknown — Zero long-term human safety data for injectable follistatin. The AAV gene-therapy trials have the longest-duration follistatin-expression follow-up but are a different therapeutic modality.
- Sourcing / counterfeit risk (the dominant practical concern) — Follistatin is a complex glycoprotein that is difficult and expensive to manufacture at biologically active quality. Research-chemical vendors sell material of widely varying purity, folding, and true-protein content. Analytical verification (HPLC-MS plus, ideally, cell-based bioassay confirming myostatin-binding activity) is essentially absent in the community market. Assume most cheap follistatin is degraded, misfolded, or counterfeit.
- WADA prohibited — Follistatin and myostatin inhibitors are prohibited at all times under S2 (peptide hormones, growth factors, and related substances — specifically "myostatin inhibitors"). Detection methods evolving. Tested athletes should not use.
- Cancer concern — Myostatin signaling has tumor-suppressive functions in some tissues. Chronic broad inhibition could theoretically promote growth of occult malignancies. Absolute contraindication in any history of cancer or precancerous lesion.
- Pregnancy and reproductive-age women — Contraindicated. Follistatin's role in reproductive biology is broader than muscle.
- Pediatric use — Not appropriate. Growth-plate effects and developmental consequences unknown.
Bloodwork & Monitoring
No formal monitoring framework exists. Reasonable monitoring given the safety profile:
- Pre-initiation cancer screening — Age-appropriate workup given the theoretical myostatin-inhibition cancer concern.
- Reproductive hormones (men) — Total and free testosterone, LH, FSH, estradiol, SHBG, prolactin at baseline and at 6–8 weeks. FS-344 in particular may perturb this panel.
- Reproductive hormones (women) — Not recommended in women of reproductive age. Not recommended during pregnancy or lactation.
- CMP (liver, kidney, glucose) — Baseline and at 6–8 weeks. Watch for rapid body-composition-associated metabolic changes.
- CBC with differential — Baseline and at 6–8 weeks given the activin-pathway hematopoietic involvement.
- CK (creatine kinase) — Baseline and periodically during rapid training-plus-follistatin cycles. Elevated CK signals muscle breakdown that may outpace recovery.
- Lipid panel — Standard cardiometabolic tracking.
- ECG and cardiac imaging — Baseline ECG is prudent. Echocardiogram at baseline and at 6–12 months in chronic users given the theoretical cardiac-remodeling concern, particularly at higher doses or longer cycles.
- Body composition (DXA or bioimpedance) — Objective tracking of lean and fat mass changes. DXA is the gold standard.
- Tendon health — Soft-tissue injury risk. Symptoms-driven evaluation; avoid maximal-load testing during cycles.
- Follistatin / myostatin levels (research only) — Assays exist but are not standardized for therapeutic monitoring.
Commonly Stacked With
Community protocols sometimes combine follistatin (releasing the myostatin brake) with IGF-1 LR3 (providing anabolic growth signal). Layered mechanism for aggressive hypertrophy. Very limited evidence for additive safety; unquantified cardiac and cancer concerns.
Growth hormone secretagogues provide systemic anabolic environment alongside follistatin's myostatin-pathway effect. Classic community GH-stack layered with follistatin for recomposition goals. Not trial-validated.
Creatine + protein (3–5 g creatine, 1.6–2.2 g/kg protein)
The non-pharmacologic substrate. Creatine monohydrate has the strongest evidence base of any muscle-performance supplement; adequate protein intake is the rate-limiting nutritional input for hypertrophy. These foundations should be in place before any peptide layer.
Progressive resistance training
Mechanical load is the primary stimulus for muscle growth. Pharmacologic myostatin inhibition without a training stimulus produces suboptimal hypertrophy. The community literature for follistatin assumes concurrent heavy resistance training.
TRT / testosterone (when medically indicated)
Hypogonadal men receiving TRT may see additive muscle gain with follistatin. This combines two biologically powerful anabolic axes with very limited combined-safety data. Not appropriate in eugonadal users chasing pharmacologic optimization.
→ Check compound compatibility in the Stack Builder
Regulatory Status
Current Status — April 2026
Recombinant follistatin-344 and follistatin-315 are not FDA-approved for any indication. Clinical development in the follistatin space is concentrated in AAV-follistatin gene therapy programs (Nationwide Children's Hospital and related academic centers), not in recombinant-protein injectable formulations. The AAV-follistatin IBM and BMD gene-therapy trials have not resulted in FDA approval as of April 2026; the modality is distinct from injectable protein.
Follistatin is not on the FDA Category 2 Bulk Drug Substances peptide list targeted by HHS Secretary Robert F. Kennedy Jr.'s February 2026 reclassification announcement. That announcement focused on smaller peptides (BPC-157, GHK-Cu, KPV, etc.) where 503A/503B compounding is commercially viable. Follistatin's glycoprotein complexity makes practical 503A compounding uncommercial regardless of regulatory posture.
WADA: Follistatin and myostatin inhibitors are explicitly prohibited at all times under the S2 category (peptide hormones, growth factors, and related substances — including myostatin function-modifying agents). Detection methodology continues to evolve. Any tested athlete using follistatin faces sanction.
As a non-approved, non-compounded biologic sold through research-chemical channels, follistatin exists in a regulatory gray area for personal use. Bulk import, commercial resale, and import claiming human-use intent are subject to FDA and customs action.
Cost & Access
Follistatin-344 and follistatin-315 are available only through research-chemical vendors for laboratory research purposes. Product quality varies dramatically; complex glycoproteins require substantial manufacturing infrastructure to produce at biologically active purity, and much of the research-chemical market material is likely degraded, misfolded, or counterfeit. Third-party COA documentation (HPLC-MS plus cell-based bioassay) is the minimum verification standard; the practical gap between vendor-supplied COAs and independent analytical confirmation is wide in this space.
U.S. compounding pharmacies cannot legally compound follistatin under current FDA bulk-substance rules. The complexity of the glycoprotein effectively precludes 503A-scale compounding regardless of regulation. AAV-follistatin gene therapy (an entirely different modality) is accessible only through academic clinical trials; it is not a commercial product.
Follistatin is unaffected by HHS Secretary Robert F. Kennedy Jr.'s February 2026 peptide reclassification announcement. Absent a sponsor advancing recombinant follistatin protein through the BLA pathway, the research-only status will persist. The AAV-follistatin gene therapy space may advance to approval for specific dystrophies on a multi-year timeline; this will not provide general access to injectable follistatin for community use.
Estimated pricing as of April 2026. Actual costs vary by provider, location, and prescription status. Kalios does not sell compounds.
Related Compounds
What people end up reading after follistatin:
Mechano growth factor. Muscle-specific splice variant of IGF-1 released in response to mechanical loading.
Recombinant human growth hormone (somatropin). 191-amino-acid protein used for GH deficiency and off-label performance.
PEGylated mechano growth factor. Extended-half-life MGF analogue for systemic dosing.
Ibutamoren — oral nonpeptide ghrelin-receptor agonist producing 24-hour GH/IGF-1 elevation.
Primary androgen. 19-carbon steroid hormone; the foundational anabolic and masculinizing hormone.
Key References
- McPherron AC, Lawler AM, Lee SJ. Regulation of skeletal muscle mass in mice by a new TGF-β superfamily member. Nature. 1997;387(6628):83-90. PMID: 9139826. (Myostatin discovery and knockout mouse phenotype.)
- Lee SJ, McPherron AC. Regulation of myostatin activity and muscle growth. Proc Natl Acad Sci USA. 2001;98(16):9306-9311. PMID: 11459930.
- Schuelke M, Wagner KR, Stolz LE, Hübner C, Riebel T, Kömen W, Braun T, Tobin JF, Lee SJ. Myostatin mutation associated with gross muscle hypertrophy in a child. N Engl J Med. 2004;350(26):2682-2688. PMID: 15215484. (Human case of myostatin loss-of-function.)
- Mendell JR, Sahenk Z, Malik V, Gomez AM, Flanigan KM, Lowes LP, Alfano LN, Berry K, Meadows E, Lewis S, Braun L, Shontz K, Rouhana M, Clark KR, Rosales XQ, Al-Zaidy S, Govoni A, Rodino-Klapac LR, Hogan MJ, Kaspar BK. A phase 1/2a follistatin gene therapy trial for becker muscular dystrophy. Mol Ther. 2015;23(1):192-201. PMID: 25322757. (AAV1-FS344 trial in BMD.)
- Mendell JR, Sahenk Z, Al-Zaidy S, Rodino-Klapac LR, Lowes LP, Alfano LN, Berry K, Miller N, Yalvac M, Dvorchik I, Moore-Clingenpeel M, Flanigan KM, Church K, Shontz K, Curry C, Lewis S, McColly M, Hogan MJ, Kaspar BK. Follistatin gene therapy for sporadic inclusion body myositis improves functional outcomes. Mol Ther. 2017;25(4):870-879. PMID: 28245993. (IBM gene-therapy long-term follow-up.)
- Rodino-Klapac LR, Haidet AM, Kota J, Handy C, Kaspar BK, Mendell JR. Inhibition of myostatin with emphasis on follistatin as a therapy for muscle disease. Muscle Nerve. 2009;39(3):283-296. PMID: 19208403. (Mechanistic review.)
- Kota J, Handy CR, Haidet AM, Montgomery CL, Eagle A, Rodino-Klapac LR, Tucker D, Shilling CJ, Therlfall WR, Walker CM, Weisbrode SE, Janssen PM, Clark KR, Sahenk Z, Mendell JR, Kaspar BK. Follistatin gene delivery enhances muscle growth and strength in nonhuman primates. Sci Transl Med. 2009;1(6):6ra15. PMID: 20368179.
- Haidet AM, Rizo L, Handy C, Umapathi P, Eagle A, Shilling C, Boue D, Martin PT, Sahenk Z, Mendell JR, Kaspar BK. Long-term enhancement of skeletal muscle mass and strength by single gene administration of myostatin inhibitors. Proc Natl Acad Sci USA. 2008;105(11):4318-4322. PMID: 18334646.
- Al-Zaidy SA, Sahenk Z, Rodino-Klapac LR, Kaspar B, Mendell JR. Follistatin Gene Therapy Improves Ambulation in Becker Muscular Dystrophy. J Neuromuscul Dis. 2015;2(3):185-192. PMID: 27858738.
- Lee SJ. Extracellular Regulation of Myostatin: A Molecular Rheostat for Muscle Mass. Immunol Endocr Metab Agents Med Chem. 2010;10(4):183-194. PMID: 21423858. (Review of endogenous myostatin regulation including follistatin.)
- Thompson TB, Lerch TF, Cook RW, Woodruff TK, Jardetzky TS. The structure of the follistatin:activin complex reveals antagonism of both type I and type II receptor binding. Dev Cell. 2005;9(4):535-543. PMID: 16198295. (Structural biology of follistatin-ligand binding.)
- Amthor H, Nicholas G, McKinnell I, Kemp CF, Sharma M, Kambadur R, Patel K. Follistatin complexes myostatin and antagonises myostatin-mediated inhibition of myogenesis. Dev Biol. 2004;270(1):19-30. PMID: 15136137.
- Wagner KR, Fleckenstein JL, Amato AA, Barohn RJ, Bushby K, Escolar DM, Flanigan KM, Pestronk A, Tawil R, Wolfe GI, Eagle M, Florence JM, King WM, Pandya S, Straub V, Juneau P, Meyers K, Csimma C, Araujo T, Allen R, Parsons SA, Wozney JM, Lavallie ER, Mendell JR. A phase I/IItrial of MYO-029 in adult subjects with muscular dystrophy. Ann Neurol. 2008;63(5):561-571. PMID: 18335515. (Class-reference myostatin antibody program.)
- Attie KM, Borgstein NG, Yang Y, Condon CH, Wilson DM, Pearsall AE, Kumar R, Willins DA, Seehra JS, Sherman ML. A single ascending-dose study of muscle regulator ACE-031 in healthy volunteers. Muscle Nerve. 2013;47(3):416-423. PMID: 23169607. (Soluble ActRIIB approach.)
- WADA Prohibited List 2026. World Anti-Doping Agency. wada-ama.org. (S2 category — includes myostatin inhibitors.)
- FDA. Bulk Drug Substances Nominated for Use in Compounding — 503A and 503B Categories. FDA.gov. Updated 2025–2026.
Last updated: April 2026 | Profile authored by Kalios Peptides research team