HMGB1 and cancer: In cancers, studies have reported that tumor-derived factors such as granulocyte-macrophage colony-stimulating factor (GM-CSF) [16], interleukin 6 (IL-6) [35], long non-coding RNA HOXA transcript at the distal tip (HOTTIP) [17] and high-mobility group box-1 (HMGB1) [36] can induce PD-L1 expression on neutrophils.