Epidermal Growth Factor (EGF) is a small mitogenic polypeptide (～6 kDa), which is present in many mammalian species and is distributed throughout a wide number of tissues and body fluids.? Human EGF is identical to β-urogastrone, a polypeptide which was recognized and isolated on the basis of its ability to inhibit gastric acid secretion.? EGF is a member of a growth factor family, which is characterized by the presence of 6 conserved cysteine motifs that form three disulfide bonds. The location of 3 intrachain disulfide bonds in recombinant human EGF is identical to that of mouse EGF.? EGF is homologous to a sequence contained in a 19 kDa protein of vaccinia virus,? which appears to utilize the EGF receptor to gain entry into cell? EGF is mitogenic for a variety of epidermal and epithelial cells, including fibroblasts, glial cells, mammary epithelial cells, vascular and corneal endothelial cells, bovine granulosa, rabbit chondrocytes, HeLa cells, and SV40-3T3 cells.?
