Top2α or proteasome inhibition correlates with impaired localization of Rad17 to the bridge DNA next to the midbody. (A–C) Localization of Rad17, Rad17:GFP, double-strand DNA ends (TUNEL), or Mre11 to DNA knots in BE cells, on spontaneous or HU-induced chromatin bridges. (D–I) Localization and mean intensity of Rad17 at the bridge DNA next to the midbody in the absence (control) or presence of Top2α or Mre11 siRNA, or after treatment of cells with 10 μM MG132 for 4 h. (J–L) Localization and mean intensity of Top2α at the bridge DNA next to the midbody in the absence (control) or presence of Mre11 siRNA. (M–O) Localization and mean intensity of Mre11 at the bridge DNA next to the midbody in the absence (control) or presence of Rad17 siRNA. Mean ± SD from n cells. Values in control were set to 1. ***, P < 0.001 (ANOVA and Student’s t test). Broken chromatin bridges are indicated by dotted arrows. Arrowheads indicate DNA knots. Midbodies (boxed areas) were reexported and are shown at higher magnification. Numbers below/next to each bar indicate n. Scale bars, 5 μm.