Myostatin Inhibitor
Follistatin 344 is a myostatin-binding protein studied for reducing the body's primary inhibitory signal on skeletal-muscle growth. Studies of myostatin deficiency have reported 200 to 300% more muscle than normal controls, while Follistatin 344 research focuses on satellite-cell proliferation, muscle-fibre development, and functional myostatin suppression.
Product
Research shows
Practical product identifiers and format details for professional review.
Content
3 mg
Format
Injectable
Composition
1 mg/ml per ml
Follistatin 344 binds myostatin with extremely high affinity, forming stable non-signalling complexes that prevent myostatin from engaging its activin receptor IIB (ACVR2B). With myostatin signalling suppressed, the SMAD2/3 intracellular pathway (which normally inhibits satellite cell activation and limits mTORC1 anabolic signalling) is inhibited. This allows satellite cells (muscle stem cells) to proliferate and fuse into existing fibres, mTORC1 to proceed without myostatin-driven inhibition, and net protein accretion to exceed the normal physiological ceiling. Follistatin 344 also binds activin A, with additional downstream effects on FSH regulation and bone density.
Based on published research and preclinical data. All benefits are documented under research-grade conditions.
Myostatin is the primary biological limiter of skeletal muscle size: a checkpoint that prevents excessive muscle growth in normal physiology. Follistatin 344's near-complete inhibition of circulating myostatin removes this ceiling, enabling satellite cell activation and muscle hypertrophy beyond what training alone can produce.
Genetic and pharmacological studies have reported 200 to 300% more muscle where myostatin signalling is absent. Documented human cases of myostatin deficiency also show exceptional muscle development, supporting continued research into controlled functional suppression.
Myostatin's primary cellular target is satellite cells: the muscle stem cells that fuse with existing fibres to produce hypertrophy and with each other to produce hyperplasia (new fibre formation). With myostatin neutralised, satellite cell proliferation is uninhibited, enabling structural muscle growth beyond the hypertrophy-only ceiling.
Myostatin activates SMAD2/3, which inhibits mTORC1: the master anabolic kinase. By neutralising myostatin, Follistatin 344 removes this inhibitory brake on mTORC1, allowing training-induced mTOR activation to proceed at its full anabolic potential.
Follistatin 344 also binds activin A, which shares receptor systems with myostatin. Activin inhibition supports bone mineral density and may reduce muscle wasting in sarcopenic contexts. The bone-muscle connectivity means follistatin's effects extend beyond purely skeletal muscle.
Due to Follistatin 344's potent biological activity, short cycles (10–14 days) are sufficient to produce meaningful myostatin suppression. The long post-cycle pause (3–6 months) allows natural myostatin tone to re-establish, preserving long-term receptor responsiveness.
Explore selected publications and registered trials on Follistatin 344, with links to the original sources.
5 publications from the research library.
Evidence type
Publication and key finding
Source
Evidence type
Preclinical study
Direct or closely related Follistatin evidence
Publication and key finding
Activin, a member of the transforming growth factor beta protein family, was originally isolated from gonadal fluids and stimulates the release of pituitary follicle-stimulating hormone (FSH).
Science (New York, N.Y.)
Evidence type
Observational study
Direct or closely related Follistatin evidence
Publication and key finding
Follistatin (FST) is a monomeric activin-binding and neutralization protein that has at least three isoforms in human tissues and fluids.
The Journal of clinical endocrinology and metabolism
Evidence type
Laboratory study
Direct or closely related Follistatin evidence
Publication and key finding
Follistatin (FST) and FST-like-3 (FSTL3) are activin-binding and neutralization proteins that also bind myostatin.
Endocrinology
Evidence type
Preclinical study
Follistatin mechanism or target context
Publication and key finding
The transforming growth factor-beta (TGF-beta) superfamily encompasses a large group of growth and differentiation factors playing important roles in regulating embryonic development and in maintaining tissue homeostasis in adult animals.
Nature
Evidence type
Preclinical study
Follistatin mechanism or target context
Publication and key finding
Myostatin (GDF-8) is a member of the transforming growth factor beta superfamily of secreted growth and differentiation factors that is essential for proper regulation of skeletal muscle mass in mice.
Proceedings of the National Academy of Sciences of the United States of America
5 selected studies from the wider trial library, in the order chosen for this product.
NCT06411366
NCT06730958
NCT06229899
NCT07443826
NCT07285629
Combinations used in research protocols where Follistatin 344 complements other compounds.
Follistatin 344 + IGF-1 LR3
Remove the myostatin ceiling (Follistatin) while maximally stimulating satellite cell activation and protein synthesis (IGF-1 LR3): the most mechanistically complete muscle growth stack.
View IGF-1 LR3Follistatin 344 + Ipamorelin + CJC-1295
Myostatin removal combined with endogenous GH/IGF-1 axis elevation: allowing both more anabolic signal and more satellite cell responsiveness simultaneously.
View IpamorelinLabbieux pens are designed for 30 to 31 administrations of 10 clicks. With daily use, this corresponds to approximately one month. We recommend starting with 5 clicks and building up to 10 clicks per administration. More sensitive people may use fewer clicks.
Before using our pens, consult the manual.
Follistatin 344 has limited human safety data, with most information derived from preclinical and gene-therapy studies. The primary safety consideration is its binding of activin A, which regulates FSH secretion; Follistatin 344 may transiently suppress FSH levels, which is relevant for fertility-sensitive protocols. This effect is dose- and cycle-length-dependent and reversible. Injection-site reactions are possible. The potential for off-target effects on other activin-family ligands, including GDF-11 and activin B, should be monitored. Short cycles with long breaks mitigate cumulative exposure and preserve natural myostatin homeostasis.
This public COA documents one selected production batch and is updated annually. It is not the COA for our latest available batch. Every batch has its own documentation, and partners can request the latest batch COA from our team.
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