Increased expression and activation of STAT1 in brain MVs of HIV-1–infected humans. (A) Western blot analysis showed increased expression of STAT1 and phospho-STAT1 (S727) in brain MVs of some HIV-1–seropositive patients and patients with HAD and HIVE. No phosphorylation of STAT1 at tyrosine residues was detected. (B-D) Confocal microscopy showed increased expression of STAT1 and phospho-STAT1 (S727) in brain MVs of HIV-1–seropositive and HAD HIVE patients, compared with MVs from HIV-seronegative controls. Computer-assisted semiquantitative analyses of all MV samples showed a significant increase in phospho-STAT1 (C) and STAT1 (D) in brain MVs of both HIV + no HIVE and HAD patients. (**P < .01; ***P < .001.) Original magnification of images in panel B, ×400.