A loxP site was inserted upstream of exon 2. An FRT-flanked neomycin resistance cassette with a 3' loxP site was inserted downstream of exon 4. Flp-mediated recombination removed the selection cassette. Cre-mediated recombination removed the exons 2-4. Western blot analysis confirmed the absence of protein expression in nucleus and cytoplasm extracts of liver tissue. (J:225381)