RB1 and cancer: BMI1 is overexpressed in various cancers and regulates several intracellular pathways implicated in cell proliferation (p16/Rb and/or p14ARF/MDM2/p53 pathways), invasion (activation of the Akt/GSK3β/Snail pathway) and self-renewal (NF-kB-Nanog pathways)84,85.