Induced expression of enhanced GFP (eGFP)-DNA topoisomerase 2-binding protein 1 (TopBP1) W1145R and wild-type (WT) cell lines. (a) The upper panel shows the TopBP1 signal from non-induced and induced eGFP-TopBP1 WT and W1145R cells (overexposure of the eGFP-TopBP1 and tubulin day 0 and day 1 blots from Figure 2b). In the lower panel, cells were induced to express eGFP-TopBP1 W1145R and WT by an increasing concentration (50, 200, 1000 ng/mL) of doxycycline for 24 h. (b) Fluorescence microscopy images of cells expressing either eGFP-TopBP1 W1145R or WT. For WT, cells were induced for 24 h with 200 ng/mL doxycycline, and for W1145R, for 24 h with 1000 ng/mL. The GFP signal is shown in green and Hoechst (DNA) in blue. Scale bar: 10 μm.