Indeed, the ectopic expression of BCR-ABL1 is known to impair the CXCL12-CXCR4 axis at this life stage of HSPCs; studies have found CXCL12 expression in the bone marrow stromal cells was reduced in both BCR-ABL transgenic mice and CML patients, while its level in the spleen was increased in CML mice compared to control mice [94]. This evidence concerns the gene ABL1 and chronic myelogenous leukemia, BCR-ABL1 positive.