The transforming growth factor beta (TGF-ß) superfamily is composed of more than 30 soluble dimeric cytokines. This superfamily can be divided into the TGF-ß subfamily, which includes TGF-ß, activin and nodal, and the BMP (bone morphogenetic protein) subfamily, which includes the BMPs, anti-Muellerian hormone (AMH) and growth-differentiation factors (GDFs). The receptors for TGF-ß proteins are formed by combinations of type I and type II transmembrane serine/threonine kinases. Upon stimulation by a TGF-ß ligand, these receptors autophosphorylate and recruit adaptor proteins, which transduce signals to the nucleus via the Smad family of proteins. TGF-ß proteins are synthesized as large precursor proteins that associate with other intracellular proteins to form latent TGF-ß complexes. The initiation of TGF-ß signaling requires the activation of latent TGF-ß through either proteolytic cleavage or biochemical modifications to the latent TGF-ß complex. TGF-ß plays a dual role in the development of cancer, acting as both a tumor suppressor and a promoter of cancer progression, metastasis and immune evasion. Additionally, members of the TGF-ß family (especially Nodal and BMP) play a critical role in early embryonic development, germ layer specification and regulation of stem cell fate. GeneTex offers a wide range of antibodies to study the TGF-β pathway.