A leucine to isoleucine mutation at amino acid 276 was inserted into exon 3. In addition, a loxP site was inserted upstream of the exon, and a FRT-flanked neomycin selection cassette and second loxP site were inserted downstream of exon 3. Flp-mediated recombination removed the neomycin selection cassette. Cre-mediated recombination deleted the mutated exon 3. (J:285924)