CXCR4 and leukemia: As shown in Figures 1F,G, the expression of CXCR4 in the TGF-β conditioned MSCs and Nalm-6 cells co-injection group tended to be higher than that in the MSCs and Nalm-6 cells co-injection group and the Nalm-6 cells alone injection group, indicating that the increased expression of CXCR4 might be closely related to the interaction between MSCs with CAF-like phenotype and leukemia cells.