Figure 8

Phosphorylated and total protein expression levels of p38 MAPK and ERK1/2 in MDA-MB-231 cell line treated with specific inhibitors for these MAPKs and stimulated with TGF-β1 for different periods of time. (A) MDA-MB-231 cells were pre-treated with 20 μM of PD98059 (specific ERK1/2 pharmacological inhibitor) for 1 h and then stimulated with 10 ng/mL TGF-β1 for different periods of time (0, 10 min and 3 h). Total protein lysates from these samples were used to analyze the protein expression levels of total and phosphorylated forms of p38 MAPK by Western blotting. (B) The phosphorylated and total protein expression levels of ERK 1/2 were measured by Western blotting in MDA-MB-231 cells pre-treated with 20 μM of SB203680 (p38 MAPK pharmacological specific inhibitor) for 1 h and stimulated with 10 ng/mL TGF-β1 for 0, 30 min and 1 h. These results were analyzed and used to calculate the p-p38 MAPK/total p38 MAPK and p-ERK1/2/total ERK1/2 ratios, respectively. Results are presented in graphics as mean ± standard errors from three independent experiments. The Western blotting figures are representative of one experiment. *, p < 0.05, *** and p < 0.001, all versus control (cells treated with DMSO, vehicle).