FIG. 3.

Overexpression of TRF2^ΔB induces TIFs in normal but not WS fibroblasts. 53BP1 foci and colocalization with the telomeric protein TRF1 in normal and WS fibroblasts 1 day after transduction of lentiviruses expressing the indicated proteins were detected with antibodies against 53BP1 (green) and TRF1 (red). Nuclei were visualized by DAPI staining. Arrows point at regions of 53BP1 and TRF1 colocalization. For the quantitation of 53BP1 foci and 53BP1 and TRF1 colocalization, see Fig. S1 in the supplemental material.