ABL1 and chronic myelogenous leukemia, BCR-ABL1 positive: In particular, imatinib mesylate, an ATP competitive inhibitor of the constitutively activated ABL1 tyrosine kinase of the BCR-ABL oncoprotein, resulting from the t(9,22) reciprocal chromosomal translocation (Ph+), has become a first line treatment of Ph+ Chronic Myelogenous Leukemia (CML) [1], [2].