In the context of the presumed fundamental role that increasing BCR-ABL levels play to ultimately establish malignant CML stem cells, this finding suggests that imatinib treatment reverses CML leukemogenesis by leaving behind low level BCR-ABL expressing CML stem cells (Figs. 1 and 2). Here, ABL1 is linked to chronic myelogenous leukemia, BCR-ABL1 positive.