Fig. 2.

UV irradiation mediates nuclear re-localization of Ku complex components. Immunofluorescence analysis of Ku complex components in response to UV radiation. MDA-MB-231 cells were exposed to UV radiation and processed 2.5 h later for immunofluorescence following a triton extraction and paraformaldehyde fixation protocol (T/PFA). Ku, WRN and the DNA binding protein SSRP1 re-localize from the nucleolus to the nucleoplasm after irradiation with UV. The nucleolar and ribosomal proteins RPL19 and NOP2, which interact primarily with Ku in undamaged cells remain localized in the nucleolus after UV irradiation. The stability of staining for the nucleolar marker NPM1 indicates that nucleolar integrity is preserved after UV radiation.