Human Epidermal Growth Factor is initially synthesized as a 130 kDa precursor transmembrane protein. The mature form of soluble EGF is a non-glycosylated polypeptide containing 53 amino acids with a molecular mass of 6 kDa. The mature form of EGF is located proximal to the transmembrane domain. The membrane EGF precursor is capable of binding to the EGF receptor and is bioactive. EGF is able to promote proliferation and differentiation of mesenchymal and epithelial cells. EGF is also a mitogen for fibroblasts, epithelial and endothelial cells, and promotes colony formation of epiderma.