Lgr5^tm2.1Npa

A loxP site was inserted upstream of exon 1 and a second loxP site into intron 1. The loxP sites are approximately 1.6 kb apart and flank the start codon-containing first exon. The FRT site flanked neomycin resistance gene cassette that was also inserted, was removed through subsequent flp-mediated recombination. (J:236636)