Figure 3

ATM and Chk2 activation precedes but is not required for Chk1 activation. (A) MCF7 cells were treated with 10 mM NEU for different time intervals and lysates were analysed for activation of checkpoint proteins by immunoblotting. (B and C) MCF 7 cells treated with 10 mM NEU at different time points were used for analysing DNA DSBs (neutral comet assay) and SSBs (alkaline comet assay) respectively. N = 150 cells (50 cells/experiment). Data shown are mean +/− standard error. The results for % DNA in tail and tail length are significantly different at p < 0.05 in Mann Whitney U test and student’s t test respectively. (D) MCF7 cells were treated with 10 mM NEU in presence of 10 μM KU 55933 (ATM inhibitor) or 25 μM DMNB (DNA-PK inhibitor) or a combination of both for 2 hours and lysates were analysed for activation of checkpoint proteins by immunoblotting. (E) MCF7 cells were treated with 10 mM NEU in presence of 10 μM KU 55933 for different time intervals and lysates were analysed for activation of checkpoint proteins by immunoblotting. (F) MCF7 cells were treated with 10 mM NEU in presence of 10 μM VE 821 for different time intervals and lysates were analysed for activation of checkpoint proteins by immunoblotting.