Fig. 1. Knock-in gene targeting strategy. (A) The Gli2 locus, targeting vector and knock-in alleles (third and fourth diagrams) with and without neo. The first three exons of Gli2 are shown as boxes, with white boxes representing untranslated exons and black boxes representing translated exons. The cDNA represents either the 1ki, 2ki or lzki (shown in B). CRE-mediated recombination was used to remove the neo cassette in the knock-in alleles in mice. P1-P4 represent primers for PCR genotyping. (B) Knock-in cDNA constructs. All cDNAs contain the Gli2 3' UTR followed by three SV40 polyA signals. (C) Typical ES cell Southern blot analysis. Genomic DNA from ES cells was digested with BamHI and probed with 5' and 3' probes. Different knock-in constructs gave different hybridization bands. Size in kb is shown on the left.