HMGB1 and arthritic joint disease: Thus, S100A8 is often classified as a damage-associated molecular pattern (DAMP) molecule or alarmin, which is released by activated or damaged cells under conditions of cell stress, a group that also includes S100A9, high mobility group box-1 (HMGB1) and serum amyloid A (SAA), and which are closely related to several forms of disease, including sepsis, arthritis, atherosclerosis, and cancer [15–18].