TSPO radioligand binding correlates with the presence of activated microglia identified by immunohistochemistry in situ [12] and immunohistochemistry combined with autoradiography in brain tissue [9, 13], and is elevated in illnesses known to be associated with gliosis [14], though TSPO signal also arises from astroglia and endothelial cells [15]. The gene discussed is TSPO; the disease is Gliosis.