Transforming Growth Factor-alpha (TGF-α) , also known as sarcoma growth factor, TGF-type I and ETGF, is a member of the EGF family of cytokines. TGF-α 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.Mature TGF-alpha shows approximately 93% amino acid sequence identity with mouse or rat TGF-alpha and is not species specific in its biological effects.