The insertion of the L1L2_Bact_P cassette created a deletion of size 3986 starting at position 44130535 and ending at position 44134521 of Chromosome 19 (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 was followed by a neomycin selection cassette under the control of the human beta-actin promoter, SV40 polyA, a second FRT site and a second loxP site, and subsequent cre expression excised this neomycin selection cassete. Further information on targeting strategies used for this and other IKMC alleles can be found at http://www.informatics.jax.org/mgihome/nomen/IKMC_schematics.shtml.