The L1L2_gt1 cassette was inserted at position 45091398 of Chromosome 7 upstream of the critical exons 6-8 (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 exons 6-8 at position 45093292. The critical exons 6-8 are thus flanked by loxP sites. Flp mediated recombination created the "conditional ready" (floxed). Subsequent cre expression resulted 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. (J:334420)