Abstract
Epidermal growth factor (EGF) is a mitogenic growth factor for epithelial and fibroblast cells. Upon binding to its receptor, EGF activates a receptor-associated tyrosine kinase activity that mediates the mitogenic activity of the receptor. We have used growth factors, novel tumor promoters, and other growth-modulating agents to identify mechanisms by which the binding and kinase activities of the EGF receptor are regulated. Our results indicate that there are multiple pathways for regulation of the EGF receptor by environmental and endogenous factors.