To determine whether CPEO affects the upstream signaling molecules of melanogenesis regulation, we assessed the impact of CPEO (1–100 μg/mL) on the activation of p38 MAPK, ERK1/2, and JNK in B16BL6 melanoma cells treated with 200 nM α-MSH under 2% FBS conditions, using Western blot analysis. Here, MAPK8 is linked to melanoma.