GFAP and central nervous system cancer: Immunofluorescence staining of the 2 cases of primary tumor stem cell spheres (DP3321 and DP7857) showed that the glioma tumor cell marker GFAP and the glioma tumor stem cell markers CD133, Nestin, and Sox2 were all positive (Figure 3), confirming that the extracted primary cells were stem cells originating from gliomas.