Abstract: Objective To investigate the roles of extracellular signal-regulated kinase (ERK)1, ERK2 and Cyclin D1 proteins in malignant melanoma (MM) and ordinary nevus. Methods By SP immunohistochemical method, the expression of ERK1, ERK2 and Cyclin D1 proteins was detected in 30 cases of MM and 13 cases of ordinary nevi. Results The expression of ERK1, ERK2 and Cyclin D1 proteins was higher in MMs than that in ordinary nevi (P<0.01). The expression of ERK1, ERK2 and Cyclin D1 was not correlated with Clark level and Breslow thickness. The expression of ERK1 and ERK2 was correlated with that of Cyclin D1. Conclusions ERK pathway is activated in MM and may result in Cyclin D1 over-expression, while in ordinary nevi, only expression of type A nevus cell is increased.

Key words: Melanoma, Nevus, Mitogen-activated protein kinases, Cyclin D1