PRKDC and idiopathic pulmonary fibrosis: DNA-PKcs was localized in the nucleus of normal and IPF cells (Fig. 2a, e, i & m) at this time, but this protein rarely co-localized with biotinylated CpG DNA in normal cells (Fig. 2a-h) and occasionally co-localized with nuclear biotinylated-CpG DNA in IPF cells (Fig. 2i-p, white arrowheads).