Fig. 6. Cyclin B1-GFP but not cyclin B2-GFP is stabilized in living cells arrested in mitosis by activation of the spindle checkpoint or by inhibition of the proteosome. (A) Visualization of GFP fluorescence in living cells expressing cyclin B1-GFP (left panels) or cyclin B2-GFP (right panels) after treatment with propyzamide. Arrows indicate cells arrested in mitosis. (B) Visualization of GFP fluorescence of Cyclin B1-GFP (left panels) or cyclin B2-GFP (right panels) in living cells after treatment with epoxomicin. Arrows indicate cells arrested in mitosis. Upper panels, Fluorescent images; lower panels, DIC images. Scale bars: 10 µm.