Follistatin-344 (1mg)

Follistatin-344 is a monomeric, cysteine-rich glycoprotein belonging to the follistatin family. It functions as a natural antagonist of members of the TGF-β superfamily, primarily myostatin (GDF-8) and activins. Myostatin is the main negative regulator of skeletal muscle growth — when follistatin binds to myostatin, it blocks its interaction with ActRIIB receptors, thereby lifting the brake on muscle hypertrophy. The 344 isoform is the longest sequence (344 amino acids) with a broader binding spectrum compared to the 288 and 315 isoforms. In experimental mouse models, follistatin administration increased muscle mass by 15–20% within 4 weeks, while in non-human primates, significant increases in skeletal muscle mass were observed without a change in muscle fiber type.

• Reconstitution: Add 1.0 mL of bacteriostatic water → 1 mg/mL (1000 mcg/mL).
• Loading: 100 mcg/day × 10 days · Maintenance: 100 mcg every 2nd day × 20 days.
• Storage: Lyophilized: −20 °C · after reconstitution: refrigerate 2–8 °C · use within 14–21 days.

1. Withdraw 1.0 mL of bacteriostatic water with a sterile syringe.
2. Inject slowly down the side of the vial; do not spray directly onto the powder.
3. Gently swirl until fully dissolved — do not shake (the protein is delicate).
4. Note the date and concentration (1 mg/mL); refrigerate at 2–8 °C.
5. Use within 14–21 days after reconstitution.

• Objective: Inhibit myostatin (GDF-8) and activins to support skeletal muscle growth.
• Schedule: 30-day cycle: 10 days loading (daily) + 20 days maintenance (EOD).
• Dose: 100 mcg per injection (loading & maintenance).
• Cycling: 30 days on, 4–8 weeks off.

• Loading Phase (Days 1–10): 100 mcg daily subcutaneously to saturate levels.
• Maintenance (Days 11–30): 100 mcg every 2nd day (EOD) to maintain myostatin inhibition.
• Timing: Morning or post-workout.
• Cycle Duration: 30 days; pause 4–8 weeks before repeating.
• Break between cycles: After the cycle (30 days), a 4–8 week break is recommended before repeating.

• Lyophilized: Store at −20 °C in dry, dark conditions; stable for up to 24 months.
• Reconstituted: Refrigerate at 2–8 °C; use within 14–21 days.
• Avoid freeze-thaw cycles; the protein is highly sensitive to temperature changes.

• Follistatin-344 is a protein, not a peptide — especially sensitive to temperature and mechanical stress.
• Do not shake — risk of denaturation.
• Research compound — no approved human clinical trials for dosing exist.

1. Soluble Activin Type IIB Receptor Promotes Skeletal Muscle Growth (PMC) — Administration of a soluble activin type IIB receptor promotes skeletal muscle growth independent of fiber type
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2. Follistatin Gene Delivery Enhances Muscle Growth in Nonhuman Primates — Follistatin gene delivery enhances muscle growth and strength in nonhuman primates
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3. Myostatin Signal Transduction: Biology and Therapeutic Potential — Myostatin signal transduction: biology and therapeutic potential
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4. Myostatin Inhibition in Muscle Disease — Nature Reviews Drug Discovery — Myostatin inhibition in muscle disease: progress and challenges
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5. Follistatin: A Multifunctional Regulatory Protein — Follistatin: a multifunctional regulatory protein
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