PAR1 and PAR2 signal via ERK1/2 and p38 MAP kinases to induce expression of innate immune markers. (a-b) HOKs were incubated with a selective inhibitor for ERK1/2 and its control substance, U0126 and U0124, respectively, at 500 nM or (c-d) a p38 inhibitor, SB203580 at 2-20 μM for 1 h, then stimulated with thrombin (10 U/ml) or trypsin (10 nM) for 6 h. The mRNA expression of CXCL3, CXCL5 and CCL20 was measured by QRT-PCR. Data from three different donors set up in duplicates were normalized to GAPDH. Data are given as means of normalized samples to unstimulated control ± SEM. (*p < 0.05 compared to the same condition without inhibitors). (e-f) To test the efficacy of inhibitors, HOKs were incubated with U0126 (0.5 μM) or SB203580 (20 μM) for 1 h, and then stimulated with thrombin (10 U/ml) for 2 min or trypsin (10 nM) for 15 min. The Western blot analysis was done using antibodies specific for phospho- ERK1/2, total-ERK1/2, phospho-p38 and total-p38. GAPDH was used as a control for equal loading of samples.