RNF31 is correlated with LMP1 in EBV latency, and its depletion results in a decrease of cell proliferation. (A) Cell lysates were prepared from SavI, SavIII, P3HR1, and JiJoye cells for immunoblotting with RNF31 and LMP1 antibodies. (B) IB4 cells were infected with lentivirus expressing RNF31 shRNAs; 48 h later, the cells were subjected to MTT cell proliferation assays using a kit from R&D Systems, following the manufacturer's instructions. The absorbance at a wavelength of 570 nm was recorded, using a 96-well plate reader (Turner Biosystems). RNF31 depletion significantly decreased cell proliferation 48 h after infection (P < 0.0001 and P = 0.0058 for shRNA-1 and shRNA-2, respectively; unpaired t test). Experiments were repeated at least three times, and representative results are shown. The error bars indicate SE.