GFAP and ischemia: As previously reported, astrocytes are the major cellular source of HMGB1 during stroke recovery.12 Our present study showed that the number of HMGB1 and glial fibrillary acidic protein (GFAP) double-positive cells (288±37 versus 609±64 and 255±40 versus 404±44; P<0.01 and P<0.05, respectively; Figures 1b and c) and the expression of HMGB1 (Figures 1d and e; P<0.01 and P<0.05, respectively) were all significantly increased in stroke mice regardless of housing conditions compared to their respective sham-operated group at 21 days post ischemia (d.p.i.).