MDM2 and cancer: It is currently known that 1,4-NQs inhibit cancer cell proliferation and growth due to: the induction of semiquinone radicals and super oxide formation followed by DNA strand breaks; the increase in intracellular ROS amount; the effect on DNA topoisomerase II, Itch protein and GPR55; and the induction of cell apoptosis and cell cycle arrest via regulation of caspase-3/7, p53, Mdm-2, Bcl-2 and Bax gene expression and MAPK, Akt and STAT3 signaling pathways [44,45,46,47,48,49,50,51,52].