AKT1 and head and neck squamous cell carcinoma: Similarly, in this study, we noticed that radiosensitization induced by MPSE or PGG was associated with impaired DNA repair, as evidenced by the marked decrease in the IR-induced phosphorylation of Akt and phosphorylation of ERK1/2, and increase in DNA damage response protein, γH2AX in HNSCC cells (Figure 5).