Recognizes a protein of 51-52kDa which is identified as the glial fibrillary acidic protein (GFAP). This antibody is highly specific and shows no cross-reaction with other intermediate filament proteins. This antibody stains astrocytes, glial cells, ependymal cells and their corresponding tumors. Many types of neural tumors such as neuroblastomas, Schwannomas, as well as extra-CNS tumors are not labeled. Antibody to GFAP is useful in differentiating primary gliomas from metastatic lesions in the brain and for documenting astrocytic differentiation in tumors outside the CNS.