Results of analyses in FANCD2 and control fibroblasts. a Average incidence of radiation- induced γ-H2AX foci per cell (mean ± SD) in FANCD2 (n = 4) and control fibroblasts (n = 6). The total number of γ-H2AX foci in FANCD2 fibroblasts was significantly higher at all recovery times, relative to control samples. b Percentage of FANCD2 cells displaying more than 30 γ-H2AX foci per cell within recovery time of 30 min, revealed a 2-fold increase compared to that in control fibroblasts (p < 0.05). c TIF analysis. In FANCD2 fibroblasts, in average 51.7% of nuclei were TIF-positive (displaying more than 5 TIFs per nucleus). The level of TIFs inversely correlates with telomere length (P = 0.03). Percentage of TIF positive cells significantly decreased after irradiation. At recovery time of 30 min considerable percentage of TIF positive cells disappeared at the same time when the incidence of γ-H2AX foci was maximal. Afterwards, TIFs appeared again, but in less extent and remained almost the same at all later recovery times. 24 h after DEB treatment, the percentage of TIF-positive FANCD2 cells also was reduced (p = 0.026) when compared to a self-state before treatment.