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Fig. 2 | BMC Biology

Fig. 2

From: Sustained CHK2 activity, but not ATM activity, is critical to maintain a G1 arrest after DNA damage in untransformed cells

Fig. 2

Once initiated by ATM, CHK2 kinase maintains G1 checkpoint arrest after DNA damage. a G1-synchronized cells were irradiated, and protein was harvested at the indicated timepoints after the damage for western blot analysis of CHK2 T68 and S516 phosphosites. b G1-synchronized RPE-1 cells were left unirradiated (0 Gy) or irradiated (4 Gy); irradiated cells were left untreated (UT) or treated with inhibitors for ATM (ATMi) or CHK2 (CHK2i) at the indicated times (0, 1, 16 h) and protein was harvested 1 h later (1, 2, 17 h post-damage, hpd) for western blot analysis. HSP90 served as a loading control. c G1-synchronized RPE-1 cells were treated as in b, BrdU and STLC were added at the time of IR, and cells were collected by trypsinization 40 h later for flow cytometry analysis of BrdU-positive (S-phase) cells (upper left part). In the right part, BrdU/propidium iodide plots of each experimental condition of a representative experiment are shown. In the lower left part, a bar graph represents the means and standard deviation of three independent experiments. d G1-synchronized RPE-1 cells were left unirradiated (0 Gy) or irradiated (4 Gy); irradiated cells were left untreated or treated with CHK2i at the indicated times (0, 1, 16 h) and protein was harvested 1 h later (1, 2, 17 hpd) for western blot analysis

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