Prostaglandin E2 (PGE2) is a primary product of arachidonic metabolism and is synthesized via the cyclooxygenase (COX) and prostaglandin synthase pathways. PGE2 production is a commonly used method for the detection of COX-1 and COX-2 modulation and prostaglandin synthases. Its activity influences inflammation, fertility and parturition, gastric mucosal integrity, and immune modulation. The effects of PGE2 are transduced by at least four distinct receptors designated EP1, EP2, EP3, and EP4. Regulates vertebrate haematopoietic stem cell homeostasis.