Follistatin is an autocrine, activin-binding protein that is ubiquitously expressed with highest expression levels being in the ovary and skin. Follistatin negatively regulates the signaling of transforming growth factor beta (TGF-ß) family members, such as activin, bone morphogenetic proteins (BMPs), myostatin, growth differentiation factor 11 (GDF-11), and TGF-ß1. Follistatin functions as an antagonist by binding TGF-ß family members to block interaction with their signaling receptors. Follistatin also inhibits the secretion of follicle-stimulating hormone (FSH) from the anterior pituitary.
Bioactivity Assay:Neutralization of Human Activin A induced cytotoxicity of MPC-11 cells; ED50 =200 ng/mL; Bioactivity =5.0 x 10^3 units/mg