Another signaling axis that exemplifies the duality of LSC BM homing and activation of downstream survival pathways, while also having been characterized preclinically in the context of AML and B-cell ALL chemoresistance, is the interaction between chemokine receptor 4 (CXCR4) and stromal cell-derived factor 1 (SDF-1 or CXCL12) found on BM endothelial and stromal cells [65,66]. The gene discussed is CXCR4; the disease is acute myeloid leukemia.