The L1L2_gt0 cassette was inserted at position 31839292 of Chromosome 11 upstream of the critical exon 2 (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 2 at position 31840308. The critical exon2 is thus flanked by loxP sites. Flp-mediated recombination removed the lacZ/neomycin cassette creating a"conditional ready" (floxed) allele. (J:244622)