Transforming growth factor beta 1 (TGFβ1) is the prototype of a growing superfamily of peptide growth factors and plays a prominent role in a variety of cellular processes, including cell-cycle progression, cell differentiation, reproductive function, development, motility, adhesion, neuronal growth, bone morphogenesis, wound healing, and immune surveillance. TGF-β1, TGF-β2 and TGF-β3 signal via the same heteromeric receptor complex, consisting of a ligand binding TGF-β receptor type II (TβR-II), and a TGF-β receptor type I (TβR-I). Signal transduction from the receptor to the nucleus is mediated via SMADs. TGF-β expression is found in cartilage, bone, teeth, muscle, heart, blood vessels, hematopoietic cells, lung, kidney, gut, liver, eye, ear, skin, and the nervous system.