The L1L2_gt0 cassette was inserted at a position on Chromosome 6 downstream of exon 2. The cassette is composed of an FRT-flanked lacZ sequence fused to a neomycin sequence followed by a loxP site. A second loxP site was inserted downstream of exon 3.Flp-mediated recombination removed the FRT-flanked neo cassette. (J:101977)