In vivo, limonin (200 mg/kg) diets inhibited cell proliferation and promoted apoptosis through suppressing the levels of both inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) in azoxymethane (AOM)-injected rats, therefore, it was considered that limonin has the effect of inhibiting colon cancer [19]. Here, NOS2 is linked to colonic neoplasm.