KRAS and cancer: Indeed, it has been suggested that in cancer cells the production of ROS by complex I, II, and III of the electron transport chain contributes to DNA damage and is required for cancer cell survival, Kras-induced cellular transformation and cancer metastasis (Weinberg et al., 2010; Takahashi et al., 2018; reviewed in Lunt and Vander Heiden, 2011; Reczek and Chandel, 2015; DeBerardinis and Chandel, 2016).