Epidermal Growth Factor (EGF), like all growth factors, binds to very specialized receptors on the surface of responsive cells. Intrinsic to the EGF receptor is tyrosine kinase activity, which is activated in response to EGF binding. EGF stimulates mesodermal and ectodermal origin, particularly of the skin and connective tissue. EGF inhibits certain carcinomas as well as hair follicle cells. EGF also has the effect of decreasing gastric acid secretion.
The receptor for EGF shares a similarity for the blood type A antigen; in tests, antibodies directed against the EGF receptor also bind to the blood type A antigen as well. This could play a role in the increased incidence of certain cancers with type A, and also perhaps why stomach acid secretions are lower in blood type A over other blood types.