Imatinib mesylate (Gleevec, formerly STI-571) is an approved drug for chronic myeloid leukemia (CML) (Capdeville et al., 2002) and gastrointestinal stromal tumors (GISTs) that work by selectively inhibiting BCR-ABL and tyrosine kinase (Demetri et al., 2002). Here, ABL1 is linked to chronic myelogenous leukemia, BCR-ABL1 positive.