A FRT-flanked trapping element consisting of a splice acceptor sequence followed by a neomycin resistance gene and a loxP site were inserted into introns 1-2. A second loxP site was inserted into introns 8-9 so that exons 2-8 were floxed. qRT-PCR analysis demonstrated the loss of mRNA expression in liver, muscle and bone marrow tissue from homozygous mutant mice. Western blot analysis confirmed absence of encoded protein.