Granzyme K Activates PAR-1 Figure 6. ERK1/2 is required for GrK-induced IL-6 and IL-8 production in lung fibroblasts. The effect of U0126 or SB202910 on IL-6, IL-8 and MCP-1 production following GrK (white bars) or thrombin (black bars) treatment. Cells were treated with 10 mM U0126 or 10 mM SB202910 for 45 min prior to exposure to GrK (200 nM) or thrombin (2.5 U/ml) for 24 h. Supernatants were collected and analyzed for protein production by ELISA. Data are expressed as percent change over vehicle control (1% DMSO in DMEM) 6 SEM from experiments run in triplicate. * p,0.05 when compared to GrK or thrombin treatment alone. doi:10.1371/journal.pone.0021484.g006 Figure 7. GrK induces cell proliferation in HFLs in a dose-dependent manner. (A) Cells were incubated with 100 and 200 nM of GrK for 48 h then trypsinized and counted using a hemocytometer to determine cell number. (B) PAR-1 neutralization with ATAP-2 (5 mg/ml) abolished GrK (200 nM)-induced cell proliferation. Data are expressed as mean fold change 6 SEM from three independent experiments run in triplicate. * p,0.05 compared to media control. doi:10.1371/journal.pone.0021484.g007 PLoS ONE | www.plosone.org 7 June 2011 | Volume 6 | Issue 6 | e21484