By now, it has been shown that both GBM cells and non-CNS cancers secrete high levels of glutamate [22,24,25,26] and that NMDARs in tumor cells mediate glutamatergic signaling via the ERK1/2 and CREB pathways (see Figure 5) [19,23]. The gene discussed is MAPK3; the disease is glioblastoma.