S-100 protein is a family of low molecular weight protein found in vertebrates characterized by two calcium binding sites of the helix-loop-helix conformation. There are at least 21 different types of S100 proteins. which are involved in regulation of protein phosphorylation, transcription factors, Ca++ homeostasis, the dynamics of cytoskeleton constituents, enzyme activities, cell growth and differentiation, and the inflammatory response. Synonyms: Monoclonal S100 antibody, Anti-S100 antibody, S-100 antibody, S100 Protein antibody, S100 Astrocyte Marker.