Prostaglandin E2 (PGE2) is the most physiologically abundant eicosanoid, which is produced predominantly from arachidonic acid by COX and PGES, and exists at some level in nearly all cell types. PGE2 acts on four different receptors termed EP1 through EP4 yielding an astounding array of biological effects. Reported effects of PGE2 include: potent vasodilation, smooth muscle relaxation, both anti- and pro-inflammatory activities, stimulates bone resorption, synergizes with LTB4, facilitates replication of AIDS virus, regulates sleep/wake cycle, demonstrates thermoregulatory action in the CNS, induces LHRH release from rat median eminence, demonstrates a protective effect on gastric mucosa, and regulates renal hemodynamics and sodium excretion.