The TGF-beta 1 (Transforming growth factor beta) is the first member of a large group of proteins included in the TGF-beta superfamily.
This superfamily includes the activin/inhibin family, bone morphogenetic proteins (BMPs), growth differentiation factors (GDFs) and the TGF-beta subfamily.
Members of the TGF-beta superfamily interact with cell surface protein kinase receptors to activate Smad signaling cascades.