KEAP1 and cancer: Although these ROS-activated pathways are highly efficient, cancer cells have two response mechanisms to reduce ROS overproduction and its toxic effects: the Kelch-like ECH-associated protein 1 (KEAP1)-nuclear factor erythroid 2-related factor 2 (Nrf2) pathway [93], and the GSH metabolism capable of reducing oxidative stress via aldehyde dehydrogenase (ALDH) [94].