CXCR4 and leukemia: Further, investigations were conducted into whether the SDF-1/CXCR4 signal axis is a key axis that mediates the interaction between MSCs with CAF-like phenotype and ALL cells to promote the growth and invasion of leukemia cells, and also into the underlying downstream molecular mechanism of the cross-talk between MSCs with CAF-like phenotype and B-ALL cells through in vitro experiments and the three-dimensional (3D) cell culture model.