Centrosome amplification and proliferation of untransformed cells after cleavage failure. (A) Centrosome amplification after repeated cleavage failure in RPE1 cell populations. Asynchronous cultures were treated with 0.5 µM cytochalasin D for 10 h (green bars) and split 100 h later. One culture was passaged seven times; the other was treated again with cytochalasin. This was repeated four more times. The percentages of binuclear cells after cytochalasin treatments are shown in blue. The percentages of centrosome amplification (more than four centrioles) are shown in bold with the number of cells counted shown above or below. (B) Proliferative capacity of binuclear cells and their progeny (yellow bars) and same-preparation control cells (green bars) after cytochalasin-induced cleavage failure. Bars show the percentage of cells that enter mitosis after completing the prior mitosis for each cell cycle; cells arresting in a previous cell cycle are not included. Percentages were calculated from lineages of multiple individual cells followed in one experiment. (C) Proliferative capacity of binuclear cells (yellow bars) and same-preparation control cells (green bars) after blebbistatin-induced cleavage failure. One experiment is shown on multiple cells.