A targeting vector containing loxP site flanked STOP cassette, GFP, and myc-tagged Eif2c2 coding sequence under the control of the CAG promoter was inserted in the Gt(ROSA)26Sor locus. When in the presence of Cre recombinase activity, the GFP/myc tagged Eif2c2 gene is expressed, GFP expression indicates expression of Eif2c2, and the myc epitope tag allowing affinity purification of associated miRNAs. (J:179351)