EGFR and glioblastoma: In glioblastoma, EPHA2, an RTK, was observed to mediate PDGFA/PDGFRA signaling, and EGFR, a major driver of MAPK, activates glutamate dehydrogenase (GDH1) transcription to promote glutamine metabolism through the mitogen-activated protein kinase kinase/extracellular signal-regulated kinase/ETS domain-containing protein Elk-1 (MEK/ERK/Elk-1) pathway.178 The outcome is biased signaling, skewed toward different dedifferentiated cell states, whose relative frequencies reflect the amplification genetic events.