Pitstop 2 induces multipolar spindle formation and loss of centriole cohesion. A, Representative immunofluorescence microscopy images of metaphase synchronized CHC-depleted HeLa cells or HeLa treated with pitstop 2 (30 μM), dynole 34-2 (30 μM), MLN8237 (0.3 μM) or DMSO vehicle (0.1%) showing the centrosomes (centrin 2, red) surrounded by the PCM (γ-tubulin, green). DNA shown in blue. Inset shows a zoomed in image of the centrosomes. B-E, HeLa cells treated with the indicated drugs (B and D) or siRNA (C and E) described in (A) were scored for the presence of multipolar spindles (B and C) and the poles of these spindles were scored for the number of centrioles per PCM (D and E). The graphs (mean ± S.E.M. of two independent experiments; n≥30 per sample) show the percentage of cells with these characteristics. The x-axis in D and E represent the number of centrioles per spindle pole in each metaphase cell. Statistical significance was determined by a Student’st-test (* p < 0.05, ** p < 0.01).