F
Follistatin-344
Full name: FST-344
A 344-amino-acid isoform of follistatin, an endogenous glycoprotein that binds and neutralizes myostatin (GDF-8) and activin A. Preclinical research in mice showed dramatic muscle mass increases with follistatin gene delivery. Studied as a potential treatment for muscle-wasting diseases. The two primary isoforms differ in half-life and tissue distribution.