The L1L2_Bact_P cassette was inserted at position 102558690 of Chromosome 11 upstream of the critical exon 3(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 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 3 at position 102559518. Flp-mediated recombination removed the FRT-flanked neo cassette. Germ line, cre mediated recombination removed exon 3. The mutation is predicted to result in a frameshift and creates a premature stop codon subsequent to exon 2. (J:242348)