Figure 4.

Paclitaxel promotes multi-polar spindles and ectopic cleavage furrows (a). Paclitaxel-treated mitotic MDA-MB-231 cells. Note multiple spindle poles in many cells. Numbers refer to spindle pole count. Spindles with three or more poles predominated at paclitaxel concentrations above 10 nM. Taken from Zasadil et al. [24]. (b) Time-lapse imaging of a dividing PtK cell in 10 µM paclitaxel. The SAC was slowly silenced in drug, and the cell progressed to cytokinesis. Note highly abnormal cleavage, with multiple ectopic furrows, in the last frame. Numbers refer to elapsed time (h : min). Taken from Yang et al. [37]. (c) Telophase PtK2 cells fixed and stained for DNA and myosin-II. In this experiment, the paclitaxel-treated cell (10 µM) was forced out of mitosis by inhibition of Mad2. Note formation of multiple ectopic furrows that recruit myosin-II (arrows). Taken from Shannon et al. [38].