Cre- and Flp-mediated recombination removed the promoter-driven neomycin selection cassette, the IRES-BetaGal reporter expression cassette and critical exons (exons 3 through 7) of the targeted KO-first, conditional ready, parental allele Esyt1tm1Tmss resulting in insertion of an FRT and a loxP site into intron 2 of the gene. (J:236096)