In addition, FTY720 and OSU-2S, a non-immunosuppressive analogue of FTY720, regulates antitumor effects via activating NADPH oxidase by up-regulating the gp91phox subunit expression, and subsequently activating PKCδ-caspase-3 signaling in hepatocellular carcinoma 11. The gene discussed is FMO5; the disease is hepatocellular carcinoma.