A loxP site was inserted into exon 9. An FRT-flanked neomycin resistance cassette with a 3' loxP site was inserted into exon 10. Flp-mediated recombination removed the selection cassette. The insertion of loxP sites in exons 9 and 10 inserted stop codons resulting in a null allele. Cre-mediated recombination removed exons 9 and 10. Western blot analysis confirmed the absence of protein expression in the liver and kidney.