A stop codon was created by a G to A mutation in exon 48 (W2711X) mimicking the most common myofibrillar myopathy-filaminopathy mutation in man. I addition a loxP site and FRT flanked neo cassette was inserted upstream of exon 47 and a loxP site was inserted the untranslated region of exon 48. Flp mediated recombination removed the neo cassette. RT-PCR analysis indicates mRNA levels are similar to wild-type. Protein levels are also similar to wild-type.