Although little is known about the function of antioxidant enzymes in cancer cells, it has been recently reported that antioxidant enzymes including glutathione S-transferase, glutathione peroxidase, and NADH quinine oxidoreductase-1, peroxiredoxins, thioredoxin, PPIA (cyclophilin A) protects cancer cells against oxidative stress induced apoptosis, as well as hypoxia and chemotherapy [8]. Here, TXN is linked to cancer.