ABL1 and chronic myelogenous leukemia, BCR-ABL1 positive: The known mechanisms of resistance to imatinib include mutations in the kinase domain of BCR-ABL, BCR-ABL amplification, BCR-ABL overexpression, and the persistence of quiescent CML leukemic stem cells (Braun et al., 2020; Ozgur Yurttas and Eskazan, 2020).