DPP4 and chronic myelogenous leukemia, BCR-ABL1 positive: CML stem cells (LSCs) are characterized by several surface markers, including CD25 (interleukin-2 receptor alpha chain), CD26 (dipeptidyl peptidase-4 or DPP4), and IL1-RAP (interleukin-1 receptor accessory protein) [11,12].