TGF-β (Transforming growth factor-beta superfamily members are critical regulators of cell proliferation, differentiation, morphogenesis, and pathogenesis. TGF-beta receptor is a serine/threonine kinase receptor complex that consists of two distinct transmembrane proteins known as type I and type II receptors. In response to ligand binding, the type II receptors form a stable complex with the type I receptors allowing phosphorylation and thus activation of the type I receptor kinases.