(D) Same as in (B) except MEFs were co-transduced with lentiviruses expressing all possible pairwise combinations of shRNAs for the nine TRs. Left: Heat map depicting the effects of paired KD combinations in the Reprogramming Efficiency (RE%). Shown are the average REs values from at least two independent experiments. The REs of the double KDs were evaluated against the RE of the corresponding single KDs. Right: Alkaline Phosphatase (AP) stained cultures of terminal reprogrammed MEFs upon representative single and double KDs of our shRNA-based screens. 