No differences were observed between established GBM (9.6 ± 7.7 μM) and stem-like cells (6.3 ± 3.5 μM) and although mTOR activation is important for cell cycle progression [23,24], the efficacy of RES529 seemed not to be related to PI3K/Akt/mTOR basal phosphorylation levels. This evidence concerns the gene PIK3CA and glioblastoma.