A Bcr-Abl kinase inhibitor (IC50 = 5.8 nM) that is 25- to 55-fold more potent than imatinib in vitro and ≥10-fold more potent in vivo; inhibits 12 out of the 13 most frequent imatinib-resistant Bcr-Abl point mutations, but not the T315I mutation; also targets the Src family kinase Lyn (IC50 = 19 nM)