Follistatin-344

Preclinical

Follistatin-344 (FST-344)

Category
Growth Hormone
Aliases
FST-344, FS-344
Administration
Subcutaneous injection (preclinical/research use)

How it works

  1. Binds directly to myostatin and activin A, neutralizing their ability to signal through the ACVR2B receptor that normally limits muscle fiber growth.

    Your muscles have a natural "brake pedal" called myostatin that keeps them from growing indefinitely. This peptide works by disabling that brake rather than pressing the gas.

  2. Removing this inhibitory signal allows satellite (muscle stem) cells to proliferate and fuse into new muscle fibers more readily than they otherwise would.

    With the brake released, the body's own muscle-building machinery can work more freely, which is why animal studies show such dramatic muscle growth.

Result

In animal studies, removing the myostatin brake on muscle growth produced substantial, rapid increases in muscle mass — though this dramatic effect has not been replicated or confirmed in human trials, and the compound remains unapproved for human use.