RMCE on KH2 ES cells inserted a cassette containing (from 5' to 3') a loxP-flanked pgkNEOpolyA cassette, the tetracycline responsive element (TRE or tetO), the single polycistronic expression cassette 3F2A, and SV40 intron plus polyA signal into the 3' UTR. The 3F2A cassette contains the three mouse reprogramming genes Oct4 (Pou5f1; POU domain, class 5, transcription factor 1), Klf4 (Kruppel-like factor 4 (gut)), and c-Myc (Myc; myelocytomatosis oncogene) separated by two different viral 2A oligopeptides that mediate ribosomal skipping (T2A [from insect Thosea asigna virus] and E2A [equine rhinitis A virus], respectively). (J:157298)