The targeting vector containing a 10,389 bp genomic DNA fragment spanning exon 16 of mouse Gad2 and a cassette of IRES-FlpO-loxP2272-ACE-Cre POII NeoR-loxp2272 inserted between stop codon TAA and 3' UTR was introduced into ES cells. Positive ES clones were expanded for generation of chimeric mice which have gone through self excised NeoR cassette. (J:261454)