HMGB1 and neoplasm: The death of tumor cells as a result of DNA damage by ionizing radiation, especially in the mechanism of apoptosis, is immunogenic (ICD, immunogenic cell death) because it is associated with mechanisms inducing APC maturation (APC, antigen presenting cells), i.e., calreticulin exposure on the surface of tumor cells before apoptosis, ATP release during apoptosis, and the release of intranuclear HMGB-1 protein (HMGB1: high-mobility group box 1).