The change of ERK1/2 and GSK-3β activities in the d-galactose age-induced primary cultured neonatal cardiomyocytes. The different cells were collected and subjected to western blot. The graphs represent the optical density of the band of phosphorylated ERK1/2 and GSK-3β normalized with that of total ERK1/2 and GSK-3β, respectively. All data were from four independent experiments. *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.