A neomycin selection cassette replaced a 6 kb genomic fragment containing exons 19-24, resulting in an in-frame deletion of coding sequences. Quantitative RT-PCR analysis on RNA derived from lungs, skin and skeletal muscles of homozygous mice demonstrated that a mutant transcript was produced from this allele, although approximately at ten-fold reduced levels compared to wild-type. Immunoprecipitation and immunocytochemistry experiments on fibroblasts isolated from homozygous mice confirmed that a shortened protein was made at reduced levels compared to wild-type.