Activins are dimeric growth and differentiation factors which belong to the transforming growth factor-beta (TGF-beta) superfamily of structurally related signaling proteins. Activins have a wide range of biological activities including mesoderm induction, neural cell differentiation, bone remodeling, hematopoiesis, and reproductive physiology. Activins are also involved in growth and differentiation of several tissues from different species.
Activin type I receptors transduce signals for a variety of members of the Transforming growth factor beta superfamily of ligands. This family of cytokines and hormones inlude activin, Anti-müllerian hormone (AMH), bone morphogenetic proteins (BMPs), and Nodal. They are involved in a host of physiological processes including, growth, cell differentiation, homeostasis, osteogenesis, apoptosis and many other functions.