LoxP sites were inserted into introns 2 and 5 and glutamic acid codon 257 (GAG) in exon 5 was changed to glutamine (CAG) (p.E257Q). The FRT site flanked kanamycin-neomycin resistance gene cassette that was inserted into intron 5 was removed through subsequent Flp-mediated recombination. Cre-mediated recombination removed exons 3 through 5. (J:243488)