The initial homing of B-ALL cells to the central niche is known to be mediated by interactions between CXC chemokine receptor 4 (CXCR4)-expressing B-ALL cells and CXCL12-expressing MSPCs, thus implicating the critical role of the CXCR4/CXCL12 pathway in leukemogenesis. The gene discussed is CXCR4; the disease is precursor B-cell acute lymphoblastic leukemia.