Double immunofluorescence staining for MMP-9 and GFAP demonstrate their localization in the middle cerebral artery (MCA), microvessels, and in surrounding brain tissue. MMP-9 expression in the smooth muscle cells of the MCA, micro-vessels, and brain tissue after MCAO is shown in (A) and (D) (pink arrows). GFAP expression was observed in astrocytes around the MCA, microvessels, and in the brain tissue (B and E). The merged images show the co-localization of MMP-9 and GFAP (C and F). There was no co-localization between MMP-9 and GFAP in the MCA (C), but there was some co-localization between MMP-9 and GFAP in the brain tissue and modest co-localization in the astrocytic end-feet surrounding the microvessels (white arrows).