Transforming Growth Factor beta 5 (TGF beta 5) is a member of the TGF beta family of growth factors. The TGF beta polypeptides are multifunctional; capable of influencing cell proliferation, differentiation, and other functions in a wide range of cell types. Transformed, as well as nonneoplastic tissues, release transforming growth factors; and essentially all mammalian cells possess a specific TGF receptor. The multi-modal nature of TGF beta is seen in its ability to stimulate or inhibit cellular proliferation. In general, cells of mesenchymal origin appear to be stimulated by TGF beta whereas cells of epithelial or neuroectodermal origin are inhibited by the peptide.