Transforming growth factor alpha.

Transforming growth factor alpha (TGF alpha) is a close relative of epidermal growth factor (EGF), the first polypeptide mitogen discovered in 1962 (Cohen, 1962). TGF alpha, like EGF, exerts its effect on cells through binding to the EGF-Receptor (EGF-R). Here we review the molecular and cell biology of TGF alpha before proceeding to describe our own work on signaling molecules induced in response to activation of the EGF-R.