A loxP site was inserted upstrea of exon 2 and an FRT flanked neo cassette and loxP site were introduced downstream of exon 3 via homologous recombination. Recombinase mediated recombination removed exons 2 and 3 and the neo cassette. RT-QPCR, IHC and western blot analyses confirmed the absence of mRNA and protein expression in homozygous mice. (J:187107, J:188398)