PHA-739358 and IM synergize to induce cytotoxicity in BCR-ABL–positive IM-sensitive cell lines. Dose-effect curves for monotherapy with PHA-739358 and IM and combination of both substances in K562 (A), BV173 (B), BaF3-p210 (C), BaF3-M351T (D), BaF3-E255K (E), and BaF3-T315I (F) cells after 48 hours. Proliferation was assessed by MTT assay and results were analyzed with Calcusyn software.