A loxP site was inserted upstream of exon 1 and an FRT site flanked puromycin resistance gene cassette and a second loxP site into intron 2. The puro cassette was removed through subsequent Flp-mediated recombination. Exons 1 and 2 were deleted through Cre-mediated recombination, creating a null allele. qRT-PCR and immunoblot experiments confirm the lack of expression from this allele.