PTEN and glioblastoma: Conclusively, we identified two separate subgroups of glioblastomas: (i) PTEN-positive tumors that do not display glioma cell VEGFR-2 positivity (Figure 10, left) and (ii) PTEN-negative tumors with a markedly increased likelihood of glioma cell VEGFR-2 expression (∼40% in our series; Figure 10, right).