GFAP and Alzheimer disease: AT8+ tau structures were commonly detected within AD tissue, and to a lesser extent in control tissues (Figure 1A), and while most showed little colocalization with astrocytes, some AT8+ structures in AD sections were identified in glial fibrillary acidic protein (GFAP) and S100 calcium binding protein-b (S100b)-labeled astrocytes (Figure 1A).