Transforming growth factor alpha (TGF-α) is a protein that in humans is encoded by the TGFA gene. As a member of the epidermal growth factor (EGF) family, TGF-α is a mitogenic polypeptide. The protein becomes activated when binding to receptors capable of protein kinase activity for cellular signaling. 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. This gene has been associated with many types of cancers, and it may also be involved in some cases of cleft lip/palate. TGF-α can be produced in macrophages, brain cells, and keratinocytes. TGF-α induces epithelial development. Considering that TGF-α is a member of the EGF family, 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. Cell proliferation events that involve TGF-α bound to EGFR include wound healing and embryogenesis.