The R176Q mutation, along with a new RsrII restriction site, was introduced into exon 8. A cassette containing a loxP-flanked NeoR gene expressed from the phosphoglycerate kinase promoter (PGK-NeoR) and a TetR gene was cloned in the unique BlpI site from intron 8. The loxP-flanked neomycin selection cassette was removed by Cre-mediated recombination in the final allele. (J:111780)