C: H2O2 induces loss of TRIM28 SUMOylation in HeLa cells but not in U2OS cells. HeLa or U2OS cells were mock treated or treated with 500 µM H2O2 for 5 or 15 min. Cells were lysed with 1% SDS in PBS buffer and 20 mM NEM. Upon immunoprecipitation of the SUMO1 proteome, samples were analyzed by immunoblotting with TRIM28 antibodies. 