In order to support our hypothesis that the decrease of miR-21 was determined by a selective enrichment of this miRNA in CML exosomes, we treated leukemia cells with GW4869 1 μM, (Figure 5a and b) and this treatment caused an increase of AKT phosphorylation. This evidence concerns the gene AKT1 and chronic myelogenous leukemia, BCR-ABL1 positive.