U937, K562, HL-60, and NB4 leukemia cells were transduced with lentiviruses expressing a non-targeting short hairpin RNA (shRNA) as control (shSCR) and two independent shRNAs targeting CBX2 gene (shCBX2) that display different knock-down efficacy (Supplementary Fig. 1C-F). The gene discussed is CBX2; the disease is leukemia.