A loxP site was placed in intron 36 and an FRT-loxP-neomycin-FRT-loxP cassette was introduced to intron 37 via homologous recombination. Flp-mediated recombination removed the FRT-flanked neo cassette leaving exon 37 floxed. The version of this allele that contains the neomycin selection cassette, Ank3tm3Bnt, has been analyzed. (J:218905)