ABL1 and chronic myelogenous leukemia, BCR-ABL1 positive: The t(9;22) chromosomal translocation in human leads to the formation of the BCR-ABL fusion gene that encodes a constitutively expressed and cytoplasmic-localized c-Abl kinase and has been shown to be critical for the development of chronic myelogenous leukemia (CML), acute lymphoid leukemia (ALL) and acute myelogenous leukemia (AML)3, 4, 5.