Prostaglandin E2 (PGE2) is four arachidonic acid metabolites by COX-2 catalysis, through four kinds of specific membrane G protein coupled receptors (EP1, EP2, EP3 and EP4) play a role, it can promote tumor cell proliferation, angiogenesis and metastasis, can inhibit the apoptosis of tumor cells. The gene discussed is PTGER4; the disease is neoplasm.