A loxP site was inserted upstream of exon 2, and a frt-flnaked neomycin cassette and a downstream loxP site was inserted downstream of exon 2. Transient cre recombinase expression removed exon 2 and the neomycin cassette. Despite the deletion, mRNA from the locus was still detected in heterozygous tissues including the brain and testis. Sequencing of exons 1-8 revealed the mRNA was out of frame indicating that this is a loss-of-function allele. This was confirmed through allelic complementation assays and by a lack of protein detectable in immunoblot assays.