GFAP and glioblastoma: In patients with recurrent glioblastoma, a tendency toward a negative correlation was found between the content of sEVs with the GFAP+VEGF+bright MMP2+C5b-9- phenotype and the expression of mutant p53 in the primary tumor tissue (r = −0.44, p = 0.114) (Figure 4A,B).