CXCR4 and acute lymphoblastic leukemia: The SDF-1/C-X-C chemokine receptor type 4 (CXCR4) axis, as a signaling axis facilitating the interaction between tumor cells and stromal cells, promotes the integration α5β1 on leukemia cells to bind to FN in MSCs with CAFs phenotype, thus stimulating the interaction between ALL cells and MSCs with CAFs phenotype, which may be a potential molecular mechanism that fosters the progression of ALL.