Figure 3

Chk1-suppressed cell death pathway is active in HeLa cells. Cells were treated with Gö6796 and/or IR or STS. Cell death was assessed in parallel after 24 h and 48 h of treatment by sub-G1 (a) or AnnexinV/PI staining (b). After 24 h, cells were harvested and lysed for western blot analysis to assess Chk1 inhibition (c). Activation of Chk1, Caspase-2 and Caspase-3 was monitored in parallel by western blotting (d). HeLa cells with regulated knockdown of Caspase-2 were put on doxycycline for 24 h. Impact of Caspase-2 knockdown (e) on cell death induced by Chk1 inhibition and/or IR in HeLa cells, monitored by sub-G1 analysis, is depicted in (f). Representative histograms from sub-G1 analysis are shown in (g). Bars represent means±S.E. of ≥3 independent experiments. *Indicates significant differences (P<0.05) between Casp2 proficient and deficient cells