Their work suggests that CXCL12/CXCR4 signaling may be inhibited in vivo through down-regulation of CXCL12 in the stroma by exosomal shuttle of miR-126 from CML cells to stroma (42, 54). This evidence concerns the gene CXCL12 and chronic myelogenous leukemia, BCR-ABL1 positive.