First, the expression of CXCR4 was detected in leukemia cells and normal controls (n = 3), from which CXCR4 was found to be highly expressed to varying degrees in Nalm-6, RS4;11 and primary B-ALL cells (n = 3) (P < 0.05; Figure 2A). The gene discussed is CXCR4; the disease is leukemia.