Two loxP sites were introduced into introns flanking exons 3 and 4, and an FRT site, a splice acceptor (SA) of Vamp7 exon 5, partial cDNA (exons 5-8) encoding the remainder of the gene, an IRES, a neomyin selection cassette, and a polyA tail followed by the second FRT cassette was inserted between exons 4 and 5. In male mice with the Neo resistance gene in an allele of the Vamp7 gene (Neo/Y), transcription of the Vamp7 gene is expected to be preserved, because the SA traps the Vamp7coding sequence from exons 1 to 4 and Vamp7 cDNA (exons 5-8) follows this to produce an intact transcript (exons 1-8). Recombination of the loxP sites in the germline resulted in the deletion of exons 3 and 4. Western blot analysis indicated that expression of the gene was eliminated in brain, colon, kid- ney, spleen, stomach, small intestine and lung.