The L1L2_Bact_P cassette was inserted at position 97671507 of Chromosome 1 upstream of the critical exon(s) (Build GRCm39). The cassette is composed of an FRT site followed by lacZ sequence and a loxP site. This first loxP site was followed by neomycin resistance gene under the control of the human beta-actin promoter, SV40 polyA, a second FRT site and a second loxP site. A third loxP site was inserted downstream of the targeted exon(s) at position 97672296. The critical exon(s) were thus flanked by loxP sites and subsequent Cre-mediated excision deleted the critical sequence and the neomycin selection cassette yielding this knockout reporter allele. 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.