Follistatin 344 Research Overview (also known as FST-344, Follistatin, Activin-binding protein, FLGR242)
A naturally occurring glycoprotein and potent endogenous inhibitor of myostatin and activin — TGF-β superfamily members that limit muscle growth. Follistatin 344 is the predominant muscle isoform; by neutralizing myostatin it removes the body's primary brake on muscle hypertrophy, making it a research target for muscle wasting diseases, cachexia, and performance.
What Is Follistatin 344?
Follistatin is a single-chain glycoprotein produced by folliculostellate cells of the pituitary gland and by multiple peripheral tissues. It functions as a high-affinity binding protein for TGF-β superfamily members, most critically myostatin (GDF-8) and activin A. Follistatin 344 refers to the 344-amino-acid isoform, which is the predominant extracellular form found in muscle tissue.
Myostatin: The Muscle Growth Limiter
Myostatin is an endogenous negative regulator of skeletal muscle mass. Animals and humans with naturally occurring myostatin mutations exhibit dramatic muscle hyperplasia — documented in myostatin-null cattle, dogs, sheep, and even human infants. By binding myostatin with extraordinarily high affinity (Kd in the picomolar range), Follistatin 344 effectively neutralizes this growth inhibitory signal, removing the molecular brake on satellite cell activation and myofiber hypertrophy.
Research Applications
Gene therapy studies using Follistatin 344 vectors have produced striking muscle mass increases in primate models. Clinical trials in Becker Muscular Dystrophy patients have shown favorable safety profiles and functional improvements. Recombinant Follistatin 344 protein research focuses on cachexia, sarcopenia, and age-related muscle loss as therapeutic targets.
Bone and Metabolic Effects
Beyond muscle, Follistatin 344 has demonstrated effects on bone mineral density (by inhibiting activin-mediated bone resorption) and metabolic function, including improved glucose homeostasis in animal models of obesity and diabetes.
Quick Reference
| Literature-Reported Dose Range | 100 mcg (anecdotal) |
| Literature-Reported Frequency | Once daily during short cycles |
| Literature-Reported Cycle Length | 10-30 days (anecdotal) |
| Literature-Reported Washout | 3-4 weeks minimum |
| Storage | Lyophilized: -20°C. Reconstituted: 2-8°C |
| Sites Reported in Studies | SubQ: Abdominal fat |
| Timing | Not established |
Research Indications
Muscle Growth
Myostatin Inhibition
Blocks myostatin from binding to muscle cell receptors, removing natural growth suppression
Activin A Blockade
Also inhibits activin A, providing dual-action anti-catabolic effect
Satellite Cell Activation
Research suggests direct promotion of satellite cell proliferation
Recovery
Muscular Dystrophy Research
Gene therapy trials show potential for Becker muscular dystrophy
Muscle Wasting Conditions
Under investigation for cachexia and sarcopenia
Research Protocols
As reported in cited literature and research-community logs (see Research Citations below) — not a personal dosing recommendation.
| Research Application | Dose | Frequency | Route |
|---|
| Research Protocol (Anecdotal) | 100 mcg | Once daily | SubQ |
| Higher Dose Protocol (Anecdotal) | 200 mcg | Once daily (max) | SubQ |
Timing
Recommended administration window: not established. Typical onset: poorly characterized for injectable peptide.
Peptide Interactions
Both promote muscle growth through different pathways. Theoretical synergy but no studies on combination. Increased anabolic signaling may compound risks.
Different mechanisms - BPC-157 promotes tissue repair while follistatin inhibits growth suppressors. No interaction data available.
Both involved in tissue regeneration through different pathways. No published studies on combination effects.
Some protocols combine follistatin with GH secretagogues. Different mechanisms but no safety data on combinations.
Both promote anabolic effects. Theoretical additive muscle growth but combined use increases risk of excessive growth factor stimulation. No clinical data.
Androgens increase muscle mass through androgen receptors while follistatin inhibits myostatin. Combined use studied in some animal models but human data lacking.
Both target myostatin pathway. ACE-031 was discontinued due to vascular side effects. Combining myostatin inhibitors may increase adverse event risk.
Stacking multiple myostatin inhibitors provides no proven benefit and may increase risk of off-target TGF-β pathway disruption.
Reported Research Timeline
01Injectable peptide effects poorly characterized
02Gene therapy showed 15% muscle increase at 8+ weeks
03Short half-life limits systemic effects from daily injection
Safety Notes
Included for harm-reduction awareness only, in the event this compound is encountered outside its labeled research use. Inclusion here does not imply RUO Codes endorses, recommends, or instructs human use.
Most safety data from gene therapy, not injectable peptide
Potential FSH suppression affecting reproduction
Minor LDL increase possible
Case report of vision impairment at high dose
Not recommended during pregnancy
Seek Medical Attention If:
Any vision changes (seek immediate care)
Hormonal disruption signs
Quality Indicators
Acceptable Range
Extremely limited human peptide data
Most research involves gene therapy, not injectable peptide
Acceptable Range
Very short half-life (~90 minutes)
Native follistatin rapidly cleared from circulation
Acceptable Range
WADA banned substance
Prohibited in sports since 2019
Quality Concern
Excessive dosing risk
Vision impairment reported at 10x dose. Never exceed 200mcg/day
Research Citations
- Follistatin gene delivery enhances muscle growth and strength in nonhuman primates
Kota, J., Handy, C.R., Haidet, A.M., Montgomery, C.L., Eagle, A., Rodino-Klapac, L.R., et al., 2009, Science Translational Medicine - A Phase 1/2a Follistatin Gene Therapy Trial for Becker Muscular Dystrophy
Mendell, J.R., Sahenk, Z., Malik, V., Campbell, K.J., et al., 2015, Molecular Therapy - Long-term enhancement of skeletal muscle mass and strength by single gene administration of myostatin inhibitors
Haidet, A.M., Rber, L., Montgomery, C.L., et al., 2008, Proceedings of the National Academy of Sciences - Follistatin induces muscle hypertrophy through satellite cell proliferation and inhibition of both myostatin and activin
Gilson, H., Schakman, O., Kalista, S., Lause, P., Tsuchida, K., Thissen, J.P., 2009, American Journal of Physiology - Endocrinology and Metabolism - Inhibition of myostatin with emphasis on follistatin as a therapy for muscle disease
Rodino-Klapac, L.R., Haidet, A.M., Kota, J., Handy, C., Kaspar, B.K., Mendell, J.R., 2009, Neuromuscular Disorders - An engineered human follistatin variant: insights into the pharmacokinetic and pharmocodynamic relationships
Datta-Mannan, A., Yaden, B., Engstrom, M., et al., 2013, Journal of Pharmaceutical Sciences - Central serous chorioretinopathy associated with high-dose follistatin-344: a retrospective case series
Dağ U, Çağlayan M, Öncül H, 2020, Int Ophthalmol
Research Focus
Myostatin inhibition, Muscle hypertrophy, Cachexia, Muscle wasting, Bone density, Sarcopenia
Verified Vendors Carrying Follistatin 344
Frequently Asked Questions
What should researchers watch for with Follistatin 344?
Included for harm-reduction awareness only, in the event this compound is encountered outside its labeled research use. Inclusion here does not imply RUO Codes endorses, recommends, or instructs human use.
What should researchers expect over time with Follistatin 344?
Injectable peptide effects poorly characterized
How is Follistatin 344 typically administered in research?
As reported in cited literature and research-community logs (see Research Citations below) — not a personal dosing recommendation.
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