A, percentage of mitotic and multinucleated HeLa MR cells at each time point. A, percentage of mitotic and multinucleated HeLa MR cells at each time point. HeLa MR cells were synchronized by DTB and released into medium with 0.2 μmol/L MNNG. The +Z lanes indicate that cells were treated with Z-VAD at 24 h after DTB release. At the indicated times, cells were fixed and stained with DAPI and antibody to pH3. A minimum of 500 cells was counted per time point. The bar graph was constructed using Prism GraphPad software. Photographs show typical distributions of DAPI-stained (blue) and pH3-stained (pink) nuclei at 48-, 72-, and 96-h time points. B, percent of normal and abnormal mitotic and multinucleated cells at 72 h after synchronization by DTB and 0.2 μmol/L MNNG treatment. Bar graph was derived from a total of 963 cells. Left, mitotic cells containing abnormal numbers of centrosomes (DAPI, α-, and γ-tubulin stained); middle, multinucleated cells [DAPI (RT-deconvolution)]; right, a normal mitotic cell (Untreated). Allen G. Schroering et al. Cancer Res 2009;69:6307-6314 ©2009 by American Association for Cancer Research