CRISPR-targeting inserted a loxP site, a fusion of exon 8 and 9, a stop site and triple polyadenylation sequence, an FRT-flanked neomycin resistance cassette, a loxP site, wild-type exon 8, and a mutated exon 9 with the human mutated C-terminal tail containing a 52 bp deletion. Flp-mediated recombination removed the selection cassette. (J:300217)