Figure 3. Dynamics of DNA damage foci in hybrid binucleated cells. (A) Representative images showing γH2AX staining at different time points (4, 7, 10, and 13 h) after PEG-induced cell fusion. Red, human genome; green, mouse genome; blue, γH2AX staining. (B) Statistical results for the average number of γH2AX foci per nucleus. Three different types of cells at each time point were analyzed in more than 20 cells. Asterisks denote statistically significant difference in the number of γH2AX foci in HCT116 nuclei between hybrids and binucleated cells. (C) Representative images of γH2AX and 53BP1 or γH2AX and Ku70 co-staining after cell fusion. Green, mouse genome; red, human genome; yellow, γH2AX; purple, 53BP1 or Ku70, respectively. (D and E) Statistical results for the average number of foci per nucleus. Asterisks denote statistically significant difference in the number of foci at different time points from more than 30 cells for each category. Bars = 20 μm. **P < 0.05, ***P < 0.001, 2-tailed t test. Mean ± SD from 2 independent experiments.