Figure 5. Exogenous H2S up-regulates the ERK1/2 pathway by activating the HB-EGF/EGFR pathway in the aged H9C2 cells. The graphs represent the optical density of the bands of phosphorylated ERK1/2 (p-ERK1/2) normalized to the expression of total ERK1/2 (t-ERK1/2). The graphs represent the optical density of the bands of c-myc, c-fos and c-jun normalized to the expression of the GAPDH signal. The expression levels in the control group were considered the basal levels, and the others are expressed as fold change from the control group. All data are the means ± S.E.M. of three determinations. * p<0.05 vs. control group; # p<0.05 vs. H/R group; & p<0.05 vs. PC group; § p<0.05 vs. H/R + NaHS group; $ p<0.05 vs. PC + NaHS group.