Figure 5

5-ALA activation of the MAPK signaling pathway. (A–C) Western blot analysis of the effects of 5-ALA on the phosphorylation levels of p38 ERK 1/2 MAPK. (D) Effect of MAPK inhibitors on the protective effect of 5-ALA on low Pi-induced cell death. SB203580 (SB), PD98059 (PD), and 5-ALA were applied with 0.5 mM Pi for 1 h (A–C) and 48 h (D). Each value represents the mean ± SEM of three determinations, based on the untreated culture (control). The significance of any difference was determined using ANOVA, followed by the Bonferroni/Dunn post-hoc test (*p < 0.05 versus control; ^† p < 0.05, ^†† p < 0.01 versus treatment with 0.5 mM Pi alone).