Expression of dominant-negative Vps4-K173Q does not prevent chromatin breakage in Src or Chk1-deficient cells. (A and C) Examples of cells with DNA bridges exhibiting broken or intact intercellular canals after labeling with a lipophilic dye. Cells were transfected with negative siRNA (control), siSrc, or siChk1, or treated with TG003 for 5 h and stained with FM 1-43FX. (B) Frequency of cells with broken DNA bridges exhibiting intact intercellular canals. Error bars show the SD from the mean from three independent experiments. 15 cells with broken chromatin bridges were analyzed per experiment. (D) Cells expressing GFP or GFP–Vps4-K173Q were transfected with Aurora B siRNA (siAurora B; siAurB) or treated as in A–C. Broken DNA bridges or intercellular canals are indicated by dotted arrows. Bars, 5 µm. (E) Percentage of DNA bridges that appear broken in GFP-positive cells. Error bars show the SD from the mean from three independent experiments. A minimum of 30 cells with chromatin bridges was analyzed per experiment. ***, P < 0.001 compared with the control. Statistically significant differences were determined by ANOVA and Student’s t test.