The insertion of the L1L2_Bact_P cassette created a deletion of size 1243 starting at position 58770103 and ending at position 58771346 of Chromosome 15 (Genome Build GRCm39). This deletion results in the removal of functionally critical exon(s). The cassette is composed of an FRT site followed by lacZ sequence and a loxP site. This first loxP site is followed by a neomycin resistance gene under the control of the human beta-actin promoter, SV40 polyA, a second FRT site and a second loxP site.