Figure 6. Effect of jineol on MAP kinase-dependent signaling in melan-a cells.
(A) Cells (5 × 105 cells/ml) were cultured for 24 h, and medium, then was replaced with fresh medium containing indicated concentrations of the test compounds for the indicated times. (B) Cells (5 × 105 cells/ml) were cultured for 24 h, and medium, then was replaced with fresh medium containing various concentrations of the test compound for 2 h. Phosphorylations of ERK and p38 MAPK were analyzed using phospho-specific ERK and p38 MAPK antibodies. Equal protein loadings were confirmed using β-actin antibodies. (C) Jineol was co-treated with selective inhibitors of ERK (U0126) and p38 (SB209190) signaling molecules in melan-a cells. MITF and tyrosinase levels were analyzed by western blotting and (D) melanin contents were also determined. Determinations were made in triplicate, and results are presented as means ± SDs. *P < 0.05, **P < 0.01, versus non-treated controls, Student’s t-test.