Figure 4.

AMPK and ERK1/2 act as master regulators of inflammation‐induced up‐regulation of MMP‐9 expression in cardiac fibroblasts. Cardiac fibroblasts were pre‐treated with (A) ERK1/2 inhibitor PD 098059 (PD, 20 μmol/L) or (B) AMPK inhibitor Compound C (CC, 20 μmol/L) for 1 h followed by stimulation with TNFα (10 ng/mL), LPS (1 μg/mL) or R‐848 (5 μg/mL) for 24 h. Left panel: MMP activities in conditioned media were measured by gelatin zymography. Right panel: Bar graph indicating quantified gelantinolytic MMP‐9 activities. Results are presented as Mean ± SEM in arbitrary units (PD: n = 5 independent experiments, CC: n = 4 independent experiments). Statistical differences were assessed using the Kruskal–Wallis test followed by post hoc testing via Mann–Whitney U test for pair‐wise comparisons between individual groups.