Effects of ATO and nilotinib on cell proliferation. Cells were treated with 1 μM ATO and 5 nM nilotinib alone or in combination for 24, 48 or 72 h, respectively. Cell proliferation was determined using a MTT assay. CML-BC cells were derived from five patients with CML-BC and data were calculated from five independent experiments. **P < 0.01 vs. control.