A 34 bp loxP sequence was inserted upstream from exon 1 and a 6.4 kb PGK-neo-HsvTK cassette flanked by two loxP sites was introduced within intron 1. The loxP-flanked selection cassette and exon 1 were removed via cre-mediated recombination. RT-qPCR confirmed reduced mRNA expression in heterozygous females. (J:208796)