The insertion of Velocigene cassette ZEN-Ub1 created a deletion of size 2488bp between positions 78556055-78558542 of Chromosome 15 (Build GRCm39). Exon 2 was replaced with a lacZ-neo cassette while preserving the endogenous translational initiation codon. Western blot analysis of whole brain lysates confirmed the complete absence of encoded protein in homozygous mutant mice.