MSCs mediate protection of chronic myelocytic leukemia (CML) cells from imatinib-induced apoptosis through reducing the activity of caspase-3 and expression of anti-apoptotic protein Bcl-xl via a CXCL12/CXCR4 axis [86]. Here, CXCR4 is linked to chronic myelogenous leukemia, BCR-ABL1 positive.