These cells respond to extracellular glutamate excess in the glioblastoma microenvironment with increasing expressions of genes related to glutamate transport and metabolism such as GRIA2 (GluA2 or AMPA receptor 2), SLC1A2 (EAAT2), SLC1A3 (EAAT1), decreasing expression of xCT and increasing expression of GLUL (glutamine synthetase) (93). Here, GLUL is linked to glioblastoma.