Background:

Follistatin (FST) is a glycosylated single-chain protein. It specifically inhibits the secretion of FSH from the pituitary.¹ Follistatin/activin-binding protein binds to heparan sulfate side chains of proteoglycans on the granulosa cell surface to regulate the various actions of activin.² Follistatin regulates a variety of biological functions, including cell proliferation, differentiation, and apoptosis. Follistatin plays a critical role in the production of multiple-organ metastasis, predominantly by inhibiting the angiogenesis.³