GLUL and central nervous system cancer: In addition to the mechanisms reviewed above, other contributors to the process of peritumoral epileptogenesis include reduced expression of glutamine synthetase in regional astrocytes, increased expression of aquaporin-4 channels in glioma cells, and reduced expression of hypoxia-inducible factor 1α (HIF-1α) and signal transducer and activator of transcription 5B (STAT5B) in glioma cells [2, 8, 9, 10•, 11].