ABL1 and cancer: Imatinib, a small molecule inhibitor targeting ABL kinase, has been widely used in the clinical treatment of CML and other Philadelphia-positive (Ph+) leukemia expressing BCR-ABL1.25,26 Since ABL kinases attenuate TGF-β signaling, we reasoned that Imatinib could restore or enhance TGF-β-induced responses in ABL1-positive cancer cells.