Figure 1 of Box 1.
Biosynthesis of prostaglandins (PGs). Arachidonic acid is released from membrane phospholipids by phospholipase A2 enzymes and converted by prostaglanding G/H synthase (PGHS), also called cyclooxygenase (COX), to PGH2 in a two-step reaction. Terminal synthases convert PGH2 into PGs and thromboxane (TXA2).