TNF and colonic neoplasm: In a study of flufenamic acid, the authors conclude that it shows two opposing effects on COX-2 expression: it induces COX-2 expression in the colon cancer cell line HT-29 and macrophage cell line RAW 264.7, but it conversely inhibits tumor necrosis factor α (TNFα)- or lipopolysaccharide (LPS)-induced COX-2 expression.