SOX9 and stroke disorder: Since subventricular zone (SVZ) neural stem cells give rise to a subpopulation of reactive astrocytes in the stroke-lesioned area to participate in glial scar formation,42 we further investigated whether reduced SVZ astrocyte proliferation decreases the number of reactive astrocytes surrounding stroke lesions, and we found an 80% reduction in proliferating SVZ astrocytes (BrdU+; Sox9+, Figures 4A and 4F).