A floxed neomycin resistance cassette was inserted into intron 6 and a single loxP site was introduced into the non-coding region of exon 6 via homologous recombination. The floxed neo cassette was removed by mating mutant animals to cre deleter strain TgN(EIIa-cre)C5379Lmgd, leaving behind a single loxP site in intron 6 and a single loxP site in exon 6. (J:81826)