Similarly, radiation survival of Glu-treated LN229 (Figure 4E) or U-87MG cells (Figure 4F) was only slightly further decreased upon combined treatment with KG-501 and memantine, highlighting a direct involvement of CREB in Glu-induced radiation resistance of glioblastoma cells and indicating that CREB is a key mediator in NMDAR-mediated DNA repair. Here, CREB1 is linked to glioblastoma.