To obtain a whole genome library that suppresses the total diversity of human mRNAs, lentiviral vector constructs and a short hairpin RNA (shRNA) expression cassette were optimized. The optimization of the vector increased the virus titer in preparations by 15-20 times. A simple shRNA structure with a 21-bp stem proved to be the most effective. Lentivector-based shRNA expression constructs were obtained by using puro(R), copGFP, or H-2K(k) as a selectable marker. The efficiency of the optimized library was demonstrated when screening for shRNAs reactivating the tumor suppressor p53 in HeLa cells. Cells carried a reporter construct ensuring p53-responsive synthesis of a fluorescent protein, which allowed selection of cells with reactivated p53 by flow cytometry.