FMO5 and cancer: A critical point in the metabolic–redox mechanisms in cancer is the “hypermetabolism” required for growth and proliferation of tumor cells which results in intracellular ROS production in the mitochondria, NADPH oxidases (NOXs), peroxisomes, and endoplasmic reticulum (ER) (Batinic-Haberle et al., 2011; Barrera, 2012).