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. This evidence concerns the gene CYBB and hepatocellular carcinoma.