This protein is part of the cellular skeleton of astrocytes. GFAP can increase in astrocytes as a result of many different brain stresses and disorders. For example, too much GFAP causes astrocytes to become choked with Roesenthal Fibers, a hallmark of Alexander disease. (Fields, R. Douglas, PhD. The Other Brain. p 35-38. NY: Simon & Schuster, 2009.)