Melanocytes are skin cells found in the upper layer of skin. They produce a pigment known as melanin, which gives skin its color. There are two types of melanin: eumelanin and pheomelanin. When skin is exposed to ultraviolet (UV) radiation from the sun or tanning beds, it causes skin damage that triggers the melanocytes to produce more melanin, but only the eumelanin pigment attempts to protect the skin by causing the skin to darken or tan. Melanoma occurs when DNA damage from burning or tanning due to UV radiation triggers changes (mutations) in the melanocytes, resulting in uncontrolled cellular growth. Learn More.