GFAP and secondary progressive multiple sclerosis: Moreover, triple immunofluorescence confocal analysis showed an unambiguous intense colocalization (white signal) among P2X7R (red), MCP-1 (green), and GFAP (blue) proteins, both in control (Figures 8A–D) and SPMS tissues (Figures 8E–H), and moreover a strong up-regulation of both P2X7R and MCP-1 during astrogliosis occurring in WM of SPMS patients (Figures 8E–H).