A loxP site was inserted upstream of exon 7 and an FRT flanked neomycin resistance gene cassette and loxP site were inserted downstream of exon 9. The neomycin cassette was removed through subsequent Flp-mediated recombination. The floxed exons 7-9 were deleted via Cre-mediated recombination. Western blot analysis confirmed the absence of full-length protein and the presence of a truncated protein lacking exons 7-9. This truncated version which lacks part of the DNA-binding domain, nuclear localization signal, and oligomerization domain, is functionally inactive as a transcription factor. (J:234561)