BCR and chronic myelogenous leukemia, BCR-ABL1 positive: Furthermore, therapeutics that target the BCR-Abl fusion protein, which is the underlying cause of disease in approximately 95% of chronic myelogenous leukemia (CML) cases, e.g., imatinib, bind and inhibit Abl kinase, but do not bind Src kinase (Seeliger et al., 2007).