NUMB and cancer: We then validated the levels of NUMB, NOTCH, and SOX2 in a number of RAB4A-high cancer cells (MDA-MB-231, PC3, and SNB19) in response to RAB4A knockdown (Fig. 2B), and in RAB4A-low cancer cells (MCF7 and H1299) in response to RAB4A over-expression (Fig. 2C).