Signaling pathways mediating melanogenesis

Pigmentation of the skin, due to the synthesis and dispersion of melanin in the epidermis, is of great cosmetic and societal significance. II is also the key physiologic defense against sun-induced injuries such as sunburn, p hotocarcinogenesis and photoaging, During recent decades, there has been a dramatic increase in skin cancers, including melanoma, due to habitual sun exposure (Rigel, 1992; Weinstock, 1989). At present, in the United States, about one in 75 individuals is projected to develop malignant melanoma duri ng his or her lifetime (Rigel, 1992). Unfortunately, progress in preventing sun-related injuries has been slow, in part due to lack of understanding o f the molecular mechanisms involved in pigmentation. This article reviews r ecent progress in identifying signal transduction pathways that mediate mel anogenesis.