High expression of GluK4 was found in GBM cell lines (Stepulak et al. (2009) [300]), but more studies are needed to shed light on the role of KARs in GBM progression and glioma-associated epilepsy since glutamate released from GBM cells could activate KARs along with AMPARs and NMDARs (Lyons et al. (2007) [97]). This evidence concerns the gene GRIK4 and glioblastoma.