Fig. 2: LPS directly induced IL-33 expression in epithelial cells in vitro.

a Dose-dependent expression of the IL-33 protein in MLE-12 cells stimulated with LPS. b Time-dependent expression of the IL-33 protein in MLE-12 cells stimulated with 100 ng/ml LPS. c–e p38, p65, and MyD88 protein expression in MLE-12 cells stimulated with 100 ng/ml LPS. f–g IL-33 protein expression in MLE-12 cells stimulated with 100 ng/ml LPS in the presence or absence of the p38 inhibitor SB-203580 or the p65 inhibitor BAY 11–7082. All experiments were repeated at least three times. *P < 0.05, **P < 0.01, ***P < 0.001.