PPARD and colonic neoplasm: However, most NSAIDs fail to influence expression of PPARβ/δ in human colon cancer cells at concentrations that cause inhibition of proliferation.31 As inflammation is common in cancer but not present in all cases, the lack of change in expression of PPARβ/δ by NSAIDs may reflect the lack of induced expression of COX2 in some colorectal cancer patients.