Genome-wide RNAi screening has become a powerful tool for dissecting individual gene function and identifying genes involved in conferring complex phenotypes.Large-scale RNA interference-based analyses have some false positive and negative reports because of so-called off-target effects and interferon response, particularly in mammalian systems, linking them to virtually every type of RNAi reagent such as siRNAs and shRNAs.Using the siRNAs and shRNAs at lowest effective concentration can effectively and expediently mitigate the off-target and interferon response.