A loxP site was inserted upstream of exon 13, and an FRT-flanked neo cassette with a 3' loxP site was inserted downstream of exon 15. This allele is created by using either Cre-mediated recombination to remove exons 13-15 and the selection cassette or Flp-mediated recombination to remove the FRT-flanked neo cassette, followed by Cre-mediated recombination to remove exons 13 to 15. The reduction in protein expression was confirmed by western blot analysis. (J:166741)