A loxP site was inserted upstream of exon 10 and a floxed EGFP/hygro cassette was inserted downstream of exon 11 via homologous recombination. Cre mediated recombination removed exon 10 and the EGFP/hygro cassette. Immunoblot analysis revealed the absence of both all wild-type isoforms and any truncated proteins in homozygous mutant mice. (J:221642)