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. It is expressed in monocytes, brain cells, keratinocytes and various tumor cells. TGF-α signals through EGFR and acts synergistically with TGF-beta to promote the proliferation of a wide range of epidermal and epithelial cells. TGF-α is a transforming growth factor that is a ligand for the epidermal growth factor receptor, which activates a signaling pathway for cell proliferation, differentiation and development. This protein may act as either a transmembrane-bound ligand or a soluble ligand. The biological actions of TGF-α and EGF are similar. For instance, TGF-α and EGF bind to the same receptor. When TGF-α binds to EGFR it can initiate multiple cell proliferation events.

> 95% as determined by SDS-PAGE