Fig. 7. BubR1-L decays prior to mitotic exit. HeLa cells were treated with nocodazole for 12 hours and the mitotic cells isolated by selective detachment. Following removal of the nocodazole, the cells were replated in various drug combinations. At the time points indicated, the cells were harvested, the mitotic index determined by microscopy, soluble proteins extracted and resolved by analytical ion exchange to determine the abundance of BubR1-L. (A) Plot of mitotic index, confirming that ZM447439-treated cells exit mitosis faster than controls. (B) Plot of the BubR1-L:BubR1-S ratio demonstrating that BubR1-L levels fall before mitotic exit, both in the presence and absence of ZM447439. (C) Plot of mitotic index following release, confirming that ZM447439 drives taxol-treated cells out of mitosis and that this can be inhibited by MG132.