This MAb recognizes a protein of ~50kDa, which is identified as Glial Fibrillary Acidic Protein (GFAP). It shows no cross-reaction with other intermediate filament proteins. GFAP is found explicitly in astroglia. GFAP is a popular marker for localizing benign astrocyte and neoplastic cells of glial origin in the central nervous system. Antibody to GFAP helps differentiate primary gliomas from metastatic lesions in the brain and document astrocytic differentiation in tumors outside the CNS.