A loxP site was introduced into intron 5 and a loxP site followed by a FRT-flanked PGK-neomycin resistance cassette were inserted into intron 7. Flp-mediated recombination removed the selection cassette. Cre-mediated recombination deleted exons 5-7 in the germline. Western blot analysis confirmed absence of protein expression in the brain and heart. (J:233338)