The BCR/ABL fusion tyrosine kinase is expressed in chronic myeloid leukemia and Philadelphia-positive (Ph+) acute lymphoblastic leukemia cells, and its inhibition by the clinically used tyrosine kinase inhibitors imatinib or dasatinib induces apoptosis of these cells. Here, ABL1 is linked to chronic myelogenous leukemia, BCR-ABL1 positive.