The insertion of Velocigene cassette ZEN-Ub1 created a deletion of size 4875bp between positions 82624943-82629817 of Chromosome 6 (Build GRCm39). Sequencing of the first exon revealed that the deletion cassette is inserted 94 bp after the start of exon 1. Western blot analysis confirmed loss of protein expression in E13.5 homozygous mutant embryos.