FIGURE 7.

Cell cycle defect and loss of viability caused by Top2 depletion were rescued by Top2(WT), Top2(2SA), and Top2Δ20. Four groups of cells were transfected with the constructs indicated on the left. After 100 μm CuSO₄ induction, the cell cycle profiles were recorded on days 5 and 14. The cells without CuSO₄ induction are shown as controls for normal cell cycle distribution. After 14 days of induction, cells expressing shRNA-1-eGFP and shRNA-2-tagBFP accumulated at sub-G₁ on day 14, and 75.4% of cells were non-viable (propidium iodide (PI)-permeable). Top2-depleted cells rescued by Top2(WT), Top2(2SA), or Top2Δ20 appeared to be viable and normal in cell cycle distribution on day 14.