For example, the main gastrointestinal effects of diclofenac (inflammation, gastritis, constipation, upper GI tract pain) are consistent with the phenotypes of COX2 knockout mice, as evidenced by the sensitization to inflammatory processes such as induction of colitis, the induction of GI edema and peritonitis seen in COX-2 knockout mice (Morteau et al., 2000). Here, PTGS2 is linked to gastritis.