MTGF alpha is an EGF-related polypeptide growth factor that signals through the EGF receptor, and stimulates the proliferation of a wide range of epidermal and epithelial cells. It is produced by monocytes, keratinocytes, and various tumor cells. TGF alpha induces transformation anchorage independence in cultured cells. Human, murine and rat TGF alpha are cross-species reactive. Recombinant human TGF alpha is a 50 amino acid polypeptide (5.5 kDa) which shares approximately 40% sequence homology with EGF, including 6 conserved cysteine residues, which form 3 intramolecular disulfide bonds.