A potent, selective DP2 antagonist (Kis = 13, 3, and 4 nM for human recombinant DP2, rat recombinant DP2 receptors, and human native DP2 from Th2 cell membranes, respectivley); inhibits chemotaxis and cytokine production of human Th2 lymphocytes with IC50 values of 28 and 19 nM, respectively; inhibits eosinophilia in rats and guinea pigs (ED50s = 0.04 and 0.01 mg/kg, respectively)