The L1L2_gt0 cassette was inserted at position 92135427 of Chromosome 8 upstream of the critical exon 3 (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 3 at position 92137108. The critical exon 3 is thus flanked by loxP sites. Cre expression without flp expression creates a reporter 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:228836)