The L1L2_gt1 cassette was inserted at position 56792283 of Chromosome 14 upstream of the critical exon(s) (Build GRCm39). The cassette is composed of an FRT flanked lacZ/neomycin sequence followed by a loxP site. An additional loxP site is inserted downstream of the targeted exon(s) at position 56793168. The critical exon(s) is/are thus flanked by loxP sites. Cre mediated recombination (without flp expression) created the reporter knockout 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.