Precocious activation of the MEN induces mitotic slippage. (A-E) Exponentially growing cells of strains SCU396 (CEN-GFP) and SCU397 (bub2Δ CEN-GFP) harboring plasmids pSCU896 (pGAL1-BFA1) or pSCU134 (empty vector) were arrested in G1 phase by α-factor treatment (10 μg/ml) for 3 h and then released from α-factor into galactose-containing SGalR medium with nocodazole (15 μg/ml) (time 0). BFA1 was overexpressed under the control of the GAL1 promoter. Green fluorescent protein (GPF)-marked centromeres of chromosome IV were monitored for sister-chromatid separation (B) and chromosome missegregation (E). Bulk chromosome segregation (nuclear division), by means of staining with 4',6-diamidino-2-phenylindole (DAPI), (C) and rebudding (D) were also monitored. Representative cells at the 6 h time point are shown in (A).