The following elements were inserted into the locus: the CAG promoter and a loxP site flanked neomycin resistance gene and STOP cassette; genomic DNA including the microRNA stem loop with 136 bp of 5' and 130 bp of 3' flanking sequence; an frt site flanked IRES-EGFP cassette; and finally a polyadenylation signal. The EGFP cassette was deleted through subsequent FLP-mediated recombination. It is possible to generate allele Gt(ROSA)26Sortm2.1(Mirn150)Rsky from this allele.