The insertion of Velocigene cassette ZEN-Ub1 created a deletion of size 2504bp between positions 139956981-139959484 of Chromosome 5 (Build GRCm39). The full coding sequence of exon 2 was replaced with beta-galactosidase and loxP-flanked neomycin casette. PCR analysis confirmed the loss of exon 2 in homozygous mutants. (J:136110, J:209758)