Cytokinesis defects in casp8^−/− B cells. (A) Two independent bcasp8^−/− B-cell lymphomas were immunostained with anti–γ-tubulin and counterstained with DAPI to visualize centrosomes and DNA, respectively. Bar indicates 10 μm. (B) Graphs depicting the percentages of WT and bcasp8^−/− tumors with 1, 2, or ≥ 3 centrosomes. (C) Abnormal spindle pole formation and chromosomal segregation defects in casp8^−/− B cells. B cells from WT mice are also shown. Cells were immunostained with anti–γ-tubulin (red) to visualize centrosomes, anti–α-tubulin (green) to visualize mitotic spindles, and counterstained with DAPI (blue) to visualize chromatin. Bar indicates 10 μm. (D) Two independent bcasp8^−/− B-cell lymphomas were immunostained with anti–α-tubulin and counterstained with DAPI to visualize multinucleated cells. Bar indicates 10 μm. (E) Graphs depicting the percentages of WT and bcasp8^−/− B-cell lymphomas with multinuclei. (F) Two independent bcasp8^−/− B-cell lymphomas were immunostained with anti–α-tubulin and counterstained with DAPI to visualize micronuclei. Bar indicates 10 μm. (G) Graphs depicting the percentages of WT and bcasp8^−/− B-cell lymphomas with micronuclei. (H) bcasp8^−/− B-cell lymphomas were immunostained with anti–α-tubulin and counterstained with DAPI to visualize cytoplasmic bridges. Bar indicates 25 μm. (I) Graphs depicting the percentages of WT and bcasp8^−/− B-cell lymphomas displaying cytoplasmic bridges. Data are presented as the means ± SD of 4 independent experiments. *P < .05 by Student t test.