ABL1 and chronic myelogenous leukemia, BCR-ABL1 positive: Imatinib, the first BCR-ABL kinase inhibitor approved for the treatment of chronic myelogenous leukemia (CML), was observed to synergize with MDM2 inhibition in two BCR-ABL-positive CML cell lines, CML-T1 and BV173 (data not shown).