RPS6KB1 and glioblastoma: Western blot analysis showed dramatically decreased phosphorylation levels of mTOR (Ser2448) and an mTOR substrate (ribosomal protein 70 S6 kinase or ribosomal protein S6 kinases, polypeptide 1 (RPS6KB1)) in EMC6-overexpressing GBM cells (Figures 4a and b).