Fig. 3. Suppression of Aurora B kinase activity compromises the spindle checkpoint. Aurora transgenic lines were induced with tetracycline for 4 hours, exposed to spindle toxins then analysed by flow cytometry to determine mitotic index, or time-lapse to measure mitotic timing. In parallel, cells were exposed to 2 µM ZM1. (A,B) Bar graphs measuring mitotic index 16 hours post addition of spindle toxins nocodazole (A) or taxol (B) showing that the Aurora B and C mutants mimic the effect of ZM1. The values represent the mean ± s.e.m. derived from three independent experiments. (C,D) Box plots measuring time spent in mitosis in the absence (C) or presence (D) of taxol, showing that the Aurora B D-N mutant mimics the effect of ZM1.