TGF-β1-mediated activation of p38 MAPK pathway in 7–9 Gestational Weeks (GW) chorionic villi. (A) Kinetic of p38 phosphorylation in first trimester chorionic villi exposed to 10 ng/mL of TGF-β1 for 0.5, 1, 2, or 4 h. Results are expressed as a variation of the ratio of phosphorylated to non-phosphorylated p38 protein expression as compared with time 0 (T0). The results are normalized to vinculin expression. Data are represented as mean +/− SEM, * p < 0.05, n = 7 different placentas. A one-way ANOVA test was applied. (B) Activation of p38 MAPK pathway in first trimester chorionic villi treated with TGF-β1 (10 ng/mL) for 48 h with or without pretreatment with SB203580 (10 µM) for 1 h. The protein expression of the phosphorylated p38/total p38 ratio was measured by Western blot. The ratio is significantly increased after 48 h of 10 ng/mL TGF-β1 treatment as compared with the untreated group and the p38 pretreatment with SB203580 inhibitor abolishes this effect. The protein expression was normalized to vinculin expression and reported to the expression of vehicle control. Data are represented as mean +/− SEM. * p < 0.05, ** p < 0.01, n = 11 different placentas. RM one-way ANOVA statistical analysis was applied. Control refers to untreated chorionic villi and vehicle refers to DMSO treatment.