FollistatinĀ also known asĀ activin-binding proteinĀ is aĀ proteinĀ that in humans is encoded by theĀ FSTĀ gene.Ā Follistatin is anĀ autocrineĀ glycoproteinĀ that is expressed in nearly all tissues of higher animals. Its primary function is the binding and bioneutralization of members of the TG