Figure 1.
Depletion of ATR abrogates the intra-S checkpoint response: (A) NHF1 cells were electroporated with NTC or ATR siRNA and UV-irradiated (sham or 2.5 J/m2) 48 h following electroporation. Cells were harvested and protein extracts examined by immunoblotting 1 h after irradiation. (B and C) Velocity sedimentation analysis of nascent DNA from NHF1 cells exposed to UVC (sham-closed squares or 2.5 J/m2-open diamonds) 48 h post-electroporation with (B) NTC or (C) ATR siRNA; the irradiated cells were incubated for 30 min and then pulse labeled with 3H-thymidine for 15 min.