HIF1A and glioblastoma: Other proteins that have been shown to regulate HIF-1α expression under hypoxic conditions leading to increased GBM cell migration and invasion include FAT atypical cadherin 1, integrins αvβ3 and αvβ5, Hypoxia-inducible protein 2 (HIG2), and geranylgeranyltransferase I (GGTI) [56,57,58,59].