Treatment with AP23464 induces apoptosis of Ba/F3 cells expressing WT Bcr-Abl, Q252H, Y253F, E255K, M351T, and H396P, but not T315I or parental Ba/F3 cells. Each Ba/F3 cell line was cultured in the presence of AP23464 (0, 50, or 100 nM) for 48 hours, harvested, stained with annexin V–PE and 7-aminoactinomycin D according to the manufacturer's instructions (Guava Nexin apoptosis kit), and examined by flow cytometry. Data collection and analysis of results were performed with a Guava Technologies PCA instrument equipped with Cytosoft software. Results based on 3 independent experiments are reported as averages ± SE.