Recombinant human HMGB1 induces ACE2 expression. Q-PCR analysis of ACE2 mRNA in indicated Calu-3 (A), HepG2 (B), Caco2 (C) and RT4 (D) cells following treatment with human HMGB1 protein (200 ng/ml) or low-dose LPS (1 ng/ml) for 3–24 h (n = 3, ANOVA test). Data represent the mean ± SD of three independent experiments, each performed in triplicate, and are presented relative to control.