Figure 4.
Anti–C-Nap1 antibody-induced centrosome splitting does not require an intact cytoskeleton. (A) Centrosome splitting caused by C-Ab injection is independent of MTs. The histogram indicates the percent of antibody-injected cells with split centrosomes when treated with nocodazole (5 μg/ml) and taxol (5 μM). Drug treatment was initiated 1–1.5 h before antibody injection and the cells were maintained throughout the injection and the following 4 h of incubation before fixation. In two independent experiments, 213 and 259 cells injected with C-Ab were counted (black bars), along with 183 and 217 cells injected with control IgG (gray bars). (B) Centrosome splitting is independent of the MF network. The histogram indicates the percent of injected cells with split centrosomes after treatment with either cytochalasin D (3 μg/ml) or BDM (10 mM). To avoid cell rounding, BDM was applied only 30 min before microinjection and cytochalasin D was applied right after injection. Cells were incubated for 4 h in the presence of drugs before they were fixed and analyzed by immunofluorescence microscopy. In two independent experiments, 150 and 211 cells injected with C-Ab were counted (black bars), along with 196 and 212 cells injected with control IgG (gray bars). (A and B) The percent of centrosome splitting observed in injected cells in the absence of drugs are indicated by dotted lines (lower line for control IgG and upper line for C-Nap1 antibodies).