Prostaglandin (PG) E2 is involved in a number of physiological and pathophysiological events in many tissues throughout the body. The biological effects of PGE2 are mediated through interaction with specific membrane-bound G-protein-coupled prostanoid EP2 receptors. There are four subtypes of the EP receptor, termed EP1, EP2, EP3 and EP4, which have been defined on the basis of their different pharmacological profiles and signal transduction pathwas.