Glial fibrillary acidic protein (GFAP) is a type of intermediate filament protein that is primarily expressed in astrocytes, which are a kind of glial cells in the central nervous system. It plays a crucial role in maintaining the structural integrity of astrocytes and providing support to neurons. GFAP helps to anchor astrocytes to the extracellular matrix and other cells, contributing to the stability of the brain tissue. Additionally, it is involved in various cellular processes such as cell signaling, migration, and proliferation of astrocytes. In clinical practice, elevated levels of GFAP in cerebrospinal fluid or blood can be an indicator of certain neurological disorders like traumatic brain injury, brain tumors, and neurodegenerative diseases, making it a potentially valuable biomarker for diagnosis and monitoring of these conditions.