MTOR and glioblastoma: Treatment with PBI-05204 has also been reported to lead to apoptotic cell death by activation of caspases 3, 8 and 9 and down-regulation of PI3kinase/mTOR pathways evidenced by reduced expression of pAKT, pS6 and p4EBP1 in GBM cells (Colapietro et al., 2020a).