Catalase, an antioxidant that catalyzes the degradation of extra/intra-cellular hydrogen peroxide and plays a key role in protecting cells against ROS, shows a restrained expression profile in hepatocellular carcinoma [20] and probably in hepatic stellate cell transformation partially due to the increase of catalase gene methylation [21] and the binding of negative regulators to the silencer elements [22,23]. This evidence concerns the gene CAT and hepatocellular carcinoma.