Western Blot Analysis of Protein Expression

Cells were harvested by centrifugation, and cell pellets were lysed with RIPA buffer (Thermo Fisher Scientific) containing protease and phosphatase inhibitors. After the determination of protein concentration, we used the Western blot procedure to analyze the lysates according to previously published protocols [47 (link)]. The primary antibodies were as follows: In order to detect the MGMT protein, a polyclonal antibody from Cell Signaling Technology (Danvers, MA, USA; #2739) was used. For cleaved caspase 3, we used a monoclonal antibody (MAB10753) from Millipore-Sigma (Burlington, MA, USA). For EBNA-1, Ea-D, Zta/ZEBRA, CHOP, TRA-1-81, and beta-actin, we used monoclonal antibodies (sc-81581, sc-58121, sc-53904, sc-166682, sc-21706, and sc-47778), which were from Santa Cruz Biotechnology. As secondary antibodies, we applied horseradish peroxidase-antibody conjugates (Jackson ImmunoResearch Laboratories, West Grove, PA, USA) according to the supplier’s recommendations. All immunoblots were repeated at least once to confirm the results. Uncropped images of Western blots along with molecular weight markers and the densitometric scanning of images are provided in the Supplementary Materials.