An IRES LacZ-neo cassette is inserted into exon 14 of the gene and 29 nucleotides are deleted within exon 14 by targeted homologous recombination. The resulting mutation causes C-terminal truncation and partial deletion of DUB active site domain due to a reading frame shift in protein translation. Western blot confirmed absence of protein product in E8.5 embryo. This is a null allele. (J:168184)