Follistatin-344
Also known as: FS-344, Follistatin 344 isoform
Overview
Follistatin-344 is a 344-amino acid isoform of the native glycoprotein follistatin, engineered for targeted research applications. Follistatin is a potent endogenous inhibitor of multiple TGF-β superfamily members, most notably myostatin and activin A, which are primary negative regulators of skeletal muscle mass. Early 2000s research in mice demonstrated that follistatin-344 gene delivery could double muscular tissue mass, establishing it as one of the most powerful anabolic signaling modulators known.
Mechanism of Action
Follistatin-344 binds with high affinity to myostatin and activin A, preventing their interaction with activin type II receptors (ActRIIA/ActRIIB) and blocking downstream SMAD2/3 signaling that inhibits muscle growth. This disinhibition allows anabolic pathways (Akt/mTOR) to proceed uninhibited. The peptide also sequesters bone morphogenetic proteins (BMPs) and may interact with other TGF-β family members. By eliminating myostatin's brake on muscle protein synthesis, it enables significant hypertrophy and hyperplasia.
Potential Benefits
- Near doubling of muscle mass in gene delivery animal models
- Myostatin and activin neutralization enabling exceptional hypertrophy
- Significant improvements in 6-minute walk test in sporadic inclusion body myositis clinical trial
- Reduction in muscle fibrosis (32% in some models)
- Potential bone density enhancement through BMP modulation
- Hair follicle growth improvements (~13% in year-long studies)
- Reduced liver fibrosis via activin pathway inhibition
Dosage Protocols
The following reflects doses used in published research studies. This is not medical advice. Consult a qualified healthcare professional.
| Typical Range | 50-200 mcg/dose, 1-3x/week |
| Beginner | 50-100 mcg twice weekly |
| Intermediate | 100-200 mcg twice weekly |
| Advanced | 200-300 mcg 3x/week (research protocols only) |
| Cycle Duration | 4-6 weeks maximum |
| Cycle Off | 8-12 weeks minimum |
The biologically active isoform that inhibits myostatin and activin A/B. Injection into target muscle groups is commonly practiced for localized growth. Extended cycles risk muscle imbalances. Medical supervision essential.
Use our Reconstitution Calculator to determine exact syringe units for your protocol.
Routes of Administration
Subcutaneous Injection High — systemic distribution
Most common administration route for research peptides. Inject into abdominal fat, thigh, or upper arm. Rotate sites. standard research dose.
Intramuscular Injection High — with slightly faster onset than SC
Alternative route when deeper delivery or faster absorption is desired. Less commonly used than SC for most research peptides.
Read our full Routes of Administration Guide for detailed comparison of all delivery methods.
Stacking Protocols
Popular research stacks involving Follistatin-344:
Anabolic Recovery Stack
Combines Follistatin-344 with healing (BPC-157) and GH-axis support (CJC-1295 + Ipamorelin) for comprehensive muscle growth and recovery.
Explore our complete Peptide Stacking Guide for more combinations and safety considerations.
Reconstitution
| Typical Vial Size | 1mg, 2mg |
|---|---|
| BAC Water | 1-2ml per 1mg vial; some protocols use 0.6% acetic acid |
| Storage | Refrigerate at 2-8°C after reconstitution; extremely sensitive to heat and agitation |
| Shelf Life | 14-21 days refrigerated; lyophilized at -20°C for long-term storage |
Need exact syringe measurements?
Amino Acid Sequence
344 amino acid glycoprotein derived from the FST gene; full sequence in UniProt P19883
Side Effects & Safety
- Potential dose-dependent cardiac, bone, and vascular effects
- Theoretical risk of non-targeted tissue effects (endometrial, ovarian)
- Nosebleeds observed in ACE-031 trials (related compound)
- Long-term safety of myostatin blockade incompletely established
Safety & Contraindications
This information is for educational purposes only. Consult a qualified healthcare provider before using any peptide.
Active Malignancy
Pregnancy / Lactation
Bleeding Disorders
Active Skin Infection at Injection Site
Pharmacokinetics
| Half-Life | Follistatin-344: ~1-2 hours; Follistatin-288: even shorter |
|---|---|
| Storage | Store lyophilized peptide at -20°C (long-term) or 2-8°C (short-term, under 30 days). Reconstituted: refrigerate at 2-8°C and use within 28-30 days. Protect from light. Do not freeze reconstituted solution. |
Synergistic Compounds
The following compounds have been studied alongside Follistatin-344 for potential complementary or synergistic effects:
Learn More
References & Further Reading
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