AKT1 and glioblastoma: Meanwhile, combined treatment of MK-2206 and KU-57788 on GBM cells cultured with pericyte CM did not show any increased effect on DDR (Fig. 5k; Supplementary information, Fig. S5k), suggesting that AKT and DNA-PKcs may function together in a signaling cascade to mediate DDR upon activation by pericyte CM.