Cisplatin is used in chemotherapy of prostate, ovary and other cancer types but unfortunately the efficiency of cisplatin treatment is frequently hampered by acquired resistance. The cytotoxic effect of cisplatin has been attributed to its binding to DNA. HMGB1 is able to bind to cisplatin-DNA adducts with high affinity and its expression levels are associated with cisplatin resistance. This study reports the interactome of HMGB1 in prostate and ovarian cancer cells treated with cisplatin.