A targeting vector was designed to insert a loxP site upstream of exon 3 and a second loxP site downstream of exon 3, followed by a frt-flanked neomycin resistance (neo) cassette. Flp-mediated recombination remvoed the neo cassette. Resulting parental mice with allele Nr3c1tm1.1Jda were crossed with actin-cre mice to delete exon 3. Mice were backcrossed to breeding out the cre transgene. (J:261396)