CXCR4 and leukemia: Here we used CRISPR-mediated disruption of Cxcr4 in leukemia cells along with expression of mutated CXCR4 variants and show that, although CXCR4 is dispensable for homing of leukemia cells to the bone marrow, CXCR4 signaling is essential for leukemia development, suggesting that CXCR4 is among the core regulators required for LSC maintenance.