A loxP site was inserted upstream of exon 2. An FRT-flanked puromycin resistance cassette with a 3' loxP site was inserted downstream of exon 4. Exons 2-4 were removed via cre-mediated recombination. Immunoblot failed to detect protein in mutant MEFs. The final allele lacks the puromycin resistance cassette. The floxed allele Cd151tm2Nki was used to generate this allele. (J:114988)