Cre-mediated recombination of Rfx3tm1Wrth resulted in the excision of floxed exon 3, leaving an FRT flanked neo. Exon 3 encodes the DNA binding domain. RT-PCR showed that the deletion of exon 3 resulted in the splicing of exon 2 to exon 4, leading to a frameshift and premature termination at an out-of-frame stop codon.