S100 Beta is a homodimeric member of the S100 superfamily. S100 is a family of Ca2+-binding proteins, comprised of 19 members that are differentially expressed in a large number of cell types. The protein has been implicated in cellular processes such as cell differentiation and growth. S100 Beta is abundant in glial cells of the central and peripheral nervous system, in melanocytes, chondrocytes, and adipocytes. It also labels Langerhans cells, histiocytes, epithelial cells, myoepithelial cells and integrating reticular cells of lymphoid tissue, and tumors originated from these cells. S100 Beta is a useful marker for diagnosis of melanoma and tumors of nervous system.