PTEN and glioblastoma: Second, PTEN mutations that weaken its inhibitory effect on Akt/mTOR signaling are frequently found in many tumors including glioblastoma (Ohgaki et al., 2004; Parsa et al., 2007; Zheng et al., 2008; Koul, 2014), which causes more complicated modulation of Akt/mTOR pathway in glioblastoma, compared with normal neurons.