A loxP site and a neo cassette within intron 25 and an additional loxP site within intron 29 were added by homologous recombination. Cre-mediated recombination removed the floxed region. Translation of the mutant mRNA is predicted to produce a truncated protein with a scrambled sequence of 15 amino acids and a premature stop. Quantitative RT-PCR showed that transcript level was five fold lower in the mutant than in the wild-type.