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. Here, PTGER1 is linked to neoplasm.