The AUC for serum calpain activity, HMGB1 levels, and combination of them when distinguishing SSc-ILD patients from SSc patients were 0.781 (p < 0.05), 0.767 (p < 0.05), and 0.833 (p < 0.05) (Fig. 4b). The gene discussed is HMGB1; the disease is systemic sclerosis.