High-mobility group box 1 protein (HMGB1) induces the activation of the receptor for advanced glycation end-products (RAGE)/extracellular signal-regulated kinase (ERK)1/2 pathway in 16HBE cells. The cells were stimulated with 400 ng/ml HMGB1 for the indicated periods of time. (A) The protein expression of Toll-like receptor (TLR)2, TLR4 and RAGE was detected by western blot analysis. HMGB1 only increased the protein expression level of RAGE. (B) The activation of 3 mitogen-activated protein kinase (MAPK) pathways [phosphorylated (p-)MAPK/total (t-)MAPK: p-ERK, t-ERK, p-p38 MAPK (p38), t-p38, p-c-Jun N-terminal kinase (JNK) and t-JNK] and phosphatidylinositol 3-kinase (PI3K)/Akt signaling pathways ws detected by western blot analysis at the indicated time points. HMGB1 induced ERK1/2, Akt and JNK phosphorylation, but did not alter p38 phosphorylation. Representatives of the 3 independent experiments are shown.