A loxP site and FRT flanked neo cassette was inserted in intron 11, an Asp to Asn mutation was introduced at position 477 in exon 12, and a loxP site was inserted in intron 12 via homologous recombination. Flp-mediated recombination removed the neo cassette. Cre mediated recombination deleted exon 12. (J:243728)