Prostaglandin receptors in the prostate activate adenylyl cyclase, resulting in cAMP-mediated smooth muscle relaxation. Several prostaglandins may relax prostate smooth muscle, including prostaglandins E1 (PGE1), E2 (PGE2), and I2 (PGI2, syn. prostacyclin), acting via their cognate receptors, including IP and EP2. In contrast, prostaglandin F2α, known as thromboxane A2, induces contractions of prostate smooth muscle.