PF-04418948 is a potent EP2 receptor antagonist (IC50 = 16 nM for human EP2 receptors). Displays over 2000-fold selectivity for EP2 receptors over EP1, EP3, EP4, DP1 amd CRTH2 receptors; exhibits <30% binding at a diverse panel of GPCRs and ion channels at a concentration of 10 μM. Inhibits PGE2-induced increases in intracellular cAMP; reverses PGE2-invoked relaxation of mouse trachea (IC50 = 2.7 nM).