PF-04418948 is a highly selective and potent antagonist of the EP2 receptor (IC50 = 16 nM), demonstrating over 2000-fold selectivity against related prostanoid receptors. It effectively inhibits PGE2-induced cAMP signaling in vitro and reverses PGE2-mediated tracheal relaxation ex vivo (IC50 = 2.7 nM), making it a valuable tool for researching EP2 function in inflammation, smooth muscle physiology, and related disease models.