A construct containing a loxP site, exon 8, a lox2272 site, FRT-flanked neomycin resistance gene cassette (PGK-neo), an inverted exon 8 containing an A to T mutation at position 983 which results in a lysine to methionine substitution at residue 328 (K328M), a loxP site and lox2272 site replaced exon 8. Flp-mediated recombination removed the PGK-neo. Normal RNA splicing is disrupted and results in a truncated transcript without exon 8-9. (J:306976)