The L1L2_st1 cassette was inserted at position 89047954 of Chromosome 15 upstream of the critical exons 8-10 (coding exons 7-9, 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 8-10 at position 89049222. The critical exons 8-10 are thus flanked by loxP sites. A "conditional ready" (floxed) allele was created by flp recombinase expression in mice carrying this allele. Subsequent cre expression results in a knockout mouse. 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.