Fig. 4

ATRA synergistically induced DNA damage in combination with TPT. a and b HL60 cells were treated with or without 40 nM TPT or 1 μM ATRA for 1 h. Alkaline comet assay was used for detection of single-strand breaks (SSBs). Representative comet images of each group were shown and 200nM TPT served as the positive control (magnification 200×). Tail Moment and Tail DNA% were analysised the data from Comet assay. Each point represents mean ± SD of three independent experiments. *Significantly different (P < 0.05) from the control, according to the Dunnett’s test. c and d AML cells were exposed to TPT (40 nM), ATRA (1 μM), or in combination for indicated times, after that protein extracts were immunoblotted with specific antibodies of γ-H2AX (c), p-Chk1/2, Chk1/2 (d)