Purity >98%. ONO-AE3-208 is an antagonist of the EP4 receptor (Ki = 1.3 nM) which less potently affects EP3, FP, and TP receptors (Ki s = 30, 790, and 2,400 nM, respectively) and is without effect on other prostanoid receptors. In wild type mice, it mimics deletion of EP4 by producing severe colitis, with epithelial loss, crypt damage, and inflammation, after treatment with 3% dextran sodium sulfate. ONO-AE3-208 has also been used to implicate EP4 signaling in immune and autoimmune responses, inflammation, and cancer.