PTGS1 and colorectal carcinoma: We studied the effect of the 3 doses of aspirin (100 mg/d, 100 mg/BID, and 300 mg/d) on CRC tissue expression of genes encoding COX-1 and COX-2 and downstream prostanoid synthases (Figures 8A–C) and prostanoid receptors vs. baseline (Figures 8D–F).