AKT1 and glioma: However, while in U87MG and C6 glioma cells (Fig. 5A, B) AKT phosphorylation status remained stable at the peak levels, in A1 mes c-myc cells (Fig. 4C), after a rapid (5 minutes) 2-fold increase, AKT phosphorylation partially declined, although remaining at a significantly higher levels as compared to control conditions, up to 60 minutes.