Alteration of cell volume is associated with specific mitotic stages. (A) Confocal images of L1210 cells are used to validate drug-induced arrest in G₂ or mitosis. Cell-cycle position is determined based on the localization of geminin-mAG, chromatin condensation, and cell shape. BF, bright field. Bar, 10 µm. (B) Proportion of L1210 cells in G₂ or mitosis 6 h after treatment with various drugs. Cells showing geminin in the nucleus and diffused chromosome are in G₂ phase; cells showing geminin in the cytoplasm and condensed chromosome are in M phase. The large cells showing diffused chromosome but no geminin are post–M phase. Number of cells measured for DMSO control, 641; 20 ng/ml ICRF, 550; 5 µM STLC, 553; 1 µg/ml nocodazole, 417; and 20 µM blebbistatin, 357. (C) Volume trajectory of a control L1210 cell. (D) L1210 cell treated with 20 ng/ml ICRF-193. The straight line and the dotted lines indicate the mean and SD of cell volume upon mitosis entry based on 20 L1210 cells shown in Fig. 1 D (see Fig. S2 C for single-cell data). (E) Cell treated with 5 µM STLC (see Fig. S2 [D and E] for single-cell data). (F) Cell treated with of 20 µM blebbistatin (see Fig. S2 E for single-cell data).