RMCE (recombinase-mediated cassette exchange) was utilized to insert tetO-GFP/RNAi:Renilla luciferase (rluc) into the Col1a1 locus. The vector contains a tetracycline responsive promoter (TRE;tetO) controlling expression of a GFP reporter and short-hairpin RNA sequence targeting luciferase embedded in the MIR30 structure. The vector was then co-electroporated with a FLPe recombinase-expressing vector into the RMCE-ready KH2 ES cells.