HMGB1 and neoplasm: Two such signals that can promote antitumor immune responses after irradiation include the translocation of calreticulin to the cell surface (Obeid et al., 2007) and the release of high-mobility group box 1 (HMGB1) by dying tumor cells, which can activate DCs through Toll-like receptor 4 (Apetoh et al., 2007).