DNA damage response to double strand breaks (DSBs) in BCR/ABL1-positive cell lines. (a) Neutral comet assay analysis of DSBs. As an DSBs inducer, 24 h treatment with 10 µM etoposide was used. DNA damage marker, the % tail DNA was used. The bars indicate SD, n = 100, *** p < 0.001, compared to the control (ANOVA and Dunnett’s a posteriori test); (b) The typical images are shown. DNA was visualized using YOYO-1 staining. Images were taken using an Olympus BX61 fluorescent microscope with objective 20×; (c) phospho-ATM and phospho-H2AX were measured after 24 h treatment with etoposide using flow cytometry and Muse™ Multi-Color DNA Damage Kit.