Fig. 7. Grp/DChk1-depleted cells display mitotic catastrophe in the presence of incompletely replicated and damaged DNA. (A) Time-lapse confocal analysis allowed normal cell-cycle progression of S2 cells transiently expressing histone H2B-GFP under control conditions. (B,C) Time-lapse confocal analysis of Grp/DChk1-depleted cells transiently expressing histone H2B-GFP and treated with 10 mM HU (B) for 15 hours or with 150 Gy (C) IR followed by 2 hours of recovery. Mitotic chromosomes were irregularly condensed and did not align in the metaphase plate. After prolonged mitosis, chromosomes separated disproportionally and micronuclei were formed. Times are indicated in minutes. Scale bars, 1 µm.