Fig. 1.

Gene targeting of Xrcc1. (A) Genomic organization of the wild-type and targeted Xrcc1 loci. Gray boxes indicate exons. Open block arrow (Puro) indicates expression cassette of puromycin-resistant gene. Shaded block arrow (DTA) indicates diphtheria toxin A chain. BamH I restriction sites are indicated by “B.” Probes used in Southern blot analysis are depicted at the Top. Plus indicates wild-type allele. P and Δ indicate targeted allele with or without the puro cassette, respectively. (B) Southern blot analysis of BamH I-digested genomic DNA from wild-type and targeted cells. Genotypes, sizes of bands, and probes are indicated. (C) Western blot analysis of protein expression in wild type (WT), XRCC1 haplodeficient (+/Δ), and XRCC1-deficient (Δ/Δ) cells. The same blot was stripped and reprobed with different monoclonal antibodies as indicated.