A loxP site was inserted upstream of exon 2 and a loxP flanked neomycin resistance cassette was inserted downstream of exon 9. The neomycin resistance cassette was deleted via electroporation of ES cells with a cre expression plasmid. Exons 2 to 9 were deleted via cre-mediated recombination. RT-qPCR and immunoblotting confirmed absence of mRNA and protein.