A short hairpin RNA directed against the insulin receptor (Insr) gene was targeted into the Rosa26 locus. The shRNA sequence is under the regulation of the tetO operator and a codon optimized tet repressor (itetR) under the control of a CAG promoter. The construct was transfected into Art B6-RMCE 68 ES cells derived from the C57BL/6 strain through Recombinase Mediated Cassette Exchange.