>95% Pure active Recombinant human Follistatin.
Determined by its ability to neutralize Activin A inhibitory effect of murine MPC-11 cells. The expected ED₅₀ is 0.1-0.4 µg/ml in the presence of 7.5 ng/ml Activin A.
Follistatin belongs to a group of structurally-diverse diffusible proteins that binds to TGF-β ligands and inhibit their activity by hindering access to signaling receptors. This naturally occurring antagonist binds to Activin, BMP-2,-4,-6,-7, Myostatin, GDF-11, and TGF-β1. Follistatin is expressed in the pituitary, ovaries, decidual cells of the endometrium, and in some other tissues. Recombinant human Follistatin is a 31.5 kDa protein containing 288 amino acids including 36 cysteine residues.