The L1L2_Bact_P cassette was inserted at position 118169843 of Chromosome 11 upstream of exon 6 (Build GRCm39). The cassette is composed of an FRT site followed by lacZ sequence and a loxP site. This first loxP site is followed by a neomycin resistance gene under the control of the human beta-actin promoter, SV40 polyA, a second FRT site and a second loxP site. A third loxP site is inserted downstream of exon 6 at position 118170516. Exon 6 is thus flanked by loxP sites. A "conditional ready" (floxed) allele was created by flp recombinase mediated removal of the lacZ and neo cassettes. (J:307419)