RB1 and cancer: Since numerous tumor suppressor proteins and oncoproteins, including p53, APC, Rb, NFAT, FOXO, p27, nucleophosmin, BCR-ABL, eIF4E, surviving, and β-catenin, harbor NES and are exported from the nucleus to the cytoplasm by XPO1 to fulfill their growth-promoting and antiapoptotic functions, nuclear-cytoplasmic transport, particularly transport mediated by XPO1, is likely an effective general target for cancer (2).