The following elements were inserted into the locus: a loxP site flanked STOP cassette (consisting of a neomycin resistance gene cassette followed by three SV40 poly(A) sites), the CMV-IE enhancer/chicken beta-actin/rabbit beta-globin (CAG) hybrid promoter, and the rat gene with a p.Met593Ser mutation. This creates a conditional-ready allele from which the rat gene will only be expressed after cre-mediated recombination to remove the STOP cassette. (J:241405)