Melanocytes are epidermal cells specialized in the synthesis and export of melanin, which protects the skin against the deleterious effects of light. We have identified a photoresponsive system in both normal and malignant melanocytes. The responsiveness of this system to white light was higher in melanoma cells. This study has contributed to the understanding of malignant transformation, and will provide input to the development of new therapies for the treatment of melanoma and depigmentary disorders.