Centrosome detachment is dynamic and reversible in cnn1^−/− cells. (A) Stills from time-lapse videos of wt (Video 1) and cnn1^−/− (Videos 2 and 3) cells transfected with GFP-tubulin. Note that partially detached centrosomes (yellow arrows) appear soon after NEBD and precede the detached centrosome phenotype (blue arrows). (bottom) The cell shown initiates anaphase but fails to go through cytokinesis. (B) Summary of results from A. For cnn1^−/− cells, mitotic timing and outcome are shown according to centrosome phenotypes. The criteria for classification were the following: partial, cells that developed partially detached centrosomes at any point during filming; detached, cells with at least one fully detached centrosome. The three cnn1^−/− cells with detached centrosomes were followed for an average of 105 min after NEBD, but they failed to initiate anaphase during filming. (C) Stills from time-lapse video of cnn1^−/− cells (Video 4) transfected with mCherry-tubulin (red) and GFP-PACT (green). (D) Low dose taxol treatment of wt and cnn1^−/− cells. Blue, DNA; red, TACC3; green, α-tubulin. Centrosome phenotypes were scored in fixed cells. n = 2; at least 150 cells were counted per experiment. Error bars represent SD. Bars, 5 µm.