An A to G change at position 847 resulting in a glycine to arginine substitution at amino acid 283 was inserted in exon 9 and a FRT and loxP-flanked neomycin selection cassette was inserted in intron 9. Mice show a reduction of mRNA levels and only aberrant spliced products from exon 9 to the neo cassette, suggesting a frame-shift after exon 9.