Figure 3

Three steps to generate the final targeted allele. (A) Illustration of the targeted allele before and after deletion of the selection cassettes. The location of the Southern probes and the restriction sites used is indicated. Filled triangles indicate loxP sites and open triangles indicate FRT sites. (B) Southern blot of tail DNA from wild-type (+/+) or heterozygous mice (fl/+) digested with BamH I (to detect the 5' targeting event) or EcoR I (to detect the 3' targeting event). (C) PCR of tail DNA from wild-type (+/+) or heterozygous mice (fl/+) using primers A2-D2 or I-3'4PCR-2. The larger PCR products indicate the presence of the remaining loxP site (A2-D2 PCR) or the FRT/loxP site (I-3'4PCR-2 PCR).