The L1L2_gt1 cassette was inserted at position 121229111 of Chromosome 11 upstream of the critical exon(s) (Build GRCm39). The cassette is composed of an FRT flanked lacZ/neomycin resistance gene sequence followed by a loxP site. An additional loxP site is inserted downstream of the targeted exon(s) at position 121229935. The critical exon(s) is/are thus flanked by loxP sites. This "conditional ready" (floxed) allele was created by flp recombinase expression in mice carrying the knockout allele. (J:298097)