TopBP1 marks sites to become TopBP1-bound UFBs from prometaphase. Representative time-lapse microscopy of TopBP1-YFP-AID (yellow), PICH-TFP (blue), and hH2B-mCherry (red) in cell line RTP151 used for quantification in Fig. 7 E (ATRi). Images were acquired every 2 min for 18 min. Bar, 3 µm.
