A loxP site, wild-type exons 11/12, FRT-flanked neomycin selection cassette, a second loxP site, and exons 11/12 containing the isoleucine to lysine substitution at amino acid 438 (p.I438K) in exon 12 replaced exons 11 and 12. The neomycin cassette was removed via flp-mediated recombination. (J:308554)