Could be a melanogenic enzyme. Identified by mass spectrometry in melanosome fractions from stage I to stage IV. Widely expressed, but very low expression, if any, in the brain (PubMed:12609765, PubMed:16609006). Expressed in the epidermis with higher levels in melanocytes compared with keratinocytes and Langerhans cells (at protein level) (PubMed:29336782). Expressed in peripheral blood, but not bone marrow mononuclear cells (PubMed:12609765). Expressed in tissue macrophages, including liver Kuppfer cells and lung alveolar macrophages, in podocytes and in some cells of the ciliary body of the eye (at protein level) (PubMed:16489096). May be overexpressed in various cancers, including melanoma and glioblastoma multiforme (PubMed:7814155, PubMed:16489096, PubMed:16609006). Up-regulated by G-CSF/CSF3 and M-CSF/CSF1 in bone marrow mononuclear cells, hence up-regulation may be linked to differentiation. Increased expression levels in glioblastoma multiforme biopsy samples correlate with poor patient survival prognosis (PubMed:16609006). Has been proposed as a potential target for antibodies coupled to cytotoxic drugs in the context of cancer immunotherapy, including that of melanoma (PubMed:16489096). The disease is caused by variants affecting the gene represented in this entry. Belongs to the PMEL/NMB family.