TGF-beta Family

TGF-beta 1 was originally identified as a secreted, disulfide-linked homodimeric protein that induced a transformed phenotype in mesenchymal cells. It has since been recognized that TGF-beta 1 is only one member of a superfamily of secreted signaling molecules consisting of a number of closely related proteins designated TGF-beta 2 - 5, as well as a number of distantly related proteins that include the inhibins and activins, Mullerian inhibitory substance, the BMPs and GDFs, and the GDNF family.