In fact, a moderate increase in ROS levels in many types of cancer cells when compared to normal cells is functional to promote cell growth and proliferation, and the maintenance of ROS homeostasis is ensured by various systems as glutathione peroxidase (GPx), gluthathione reductase (GR), thioredoxin (Trx), superoxide dismutases (SOD), catalase (CAT), and peroxiredoxin (PRX) [8]. Here, CAT is linked to cancer.