Calcyclin (S100A6) is a member of the S100 family of proteins containing 2 EF-hand calcium-binding motifs. S100 proteins are localized in the cytoplasm and/or nucleus of a wide range of cells, involved in the regulation of a number of cellular processes such as cell cycle progression and differentiation. This protein may function in stimulation of Ca2+-dependent insulin release, stimulation of prolactin secretion and exocytosis. Chromosomal rearrangements and altered expression of this gene have been implicated in melanoma.