MPC5 cells pretreated with marimastat (MM) or transfected with siRNA were stimulated with mouse TNF-α. Expression of p-EGFR, EGFR, p-ERK1/2, and ERK1/2 was assessed by Western blot. Densitometry of p-EGFR and p-ERK1/2 expression was calculated as ratios against total EGFR or ERK1/2, respectively. Data are shown as mean ± SEM. n = 3 independent experiments. *P < 0.05; **P < 0.01, 1-way ANOVA with Dunnett’s multiple comparisons test.