Similarly, DPP4 (CD26), a cell membrane enzyme that specifically disrupts the SDF1‐CXCR4 axis, has been found to be highly expressed in CML CD34+ CD38− Lin− cells, whereas its expression in normal HSCs is low/absent 19. This evidence concerns the gene CXCR4 and chronic myelogenous leukemia, BCR-ABL1 positive.