CXCR4 and acute lymphoblastic leukemia: DAazo@CMSN could home to the bone marrow TI-niche through the interaction of C-X-C motif chemokine receptor 4 (CXCR4, a chemokine receptor expressed on NALM-6 ALL CM) and stromal cell-derived factor-1 (SDF-1, a chemokine specifically secreted by bone marrow endothelial and stromal cells).