Glial fibrillary acidic protein (GFAP) is an intermediate filament protein that is mainly found in astrocytes found in the central nervous system. It is also expressed in chondrocytes, fibroblasts, myoepithelial cells, lymphocytes, and hepatic stellate cells.
GFAP is involved in the formation of the cytoskeleton and maintains its tensile strength. In addition, GFAP and vimentin (VIM) regulate the formation of vimentin fibrils – hence, regulating the shape and function of the intermediate filament. Therefore, GFAP is often used as a marker for astrocytic intracranial and intraspinal tumors. GFAP antibodies are widely used for the immunostaining of astrocytes and as the loading control for astrocytes during Western Blot.