We have previonsly demonstrated that folate deficiency (FD) could trigger the downregulation of intracellular GSH and antioxidant enzymes, particularly H2O2-metabolizing catalase (CAT) and GSH peroxidase (GPx), and increased susceptibility of human hepatoma Hep G2 cells to various oxidant stress-induced cytotoxicity [10]. The gene discussed is CAT; the disease is hepatocellular carcinoma.