(C) Shown is a bar graph depicting the effects of rescue experiments in reprogramming efficiency. MEFs undergoing reprogramming were knocked down using shRNAs for the endogenous Nanog or Irf6 expression and were co-infected with a vector expressing an shRNA-resistant human homologue of Nanog or Irf6 (hNanog OE, hIrf6 OE). Data are shown as mean ± SEM of two independent experiments. 