HMGB1 and neoplasm: Radiotherapy enhances NK cell-mediated tumor killing through multiple mechanisms: Radiation upregulates stress ligands (MICA/B, ULBP) on tumor cells, augmenting NKG2D receptor recognition; Radiation-induced DNA damage triggers NK-activating DAMPs (HMGB1, ATP); Sublethal radiation doses (1–5 Gy) preserve NK cell viability while depleting immunosuppressive Tregs in tumor models.