PTEN and glioblastoma: Further investigation of this subgroup by Soroceanu et al. (2007) demonstrated that 16/121 glioblastomas in their study displayed enhanced IGF2 expression and were associated with a lack of EGFR modifications, loss of PTEN, elevated levels of the IGF-1R, PI3K/P-Akt proliferation and poorer patient survival [231,235].