Fig. 2. Gene targeting at the human XRCC2 locus. (A) Schematic representation of the XRCC2 locus, the targeting vector and the targeted locus. Relevant XhoI (Xh), SacI (S), HincII (Hc) and XbaI (Xb) restriction sites, and the position of the probe used for Southern blot analysis are shown. The positions of the primers used for PCR are indicated by arrows. Exon III is indicated by a numbered solid box. (B) Southern blot analysis of DNA from HCT116 cells digested with HincII or XbaI. Both blots were hybridized with the probe indicated in (A).