NANOG and glioblastoma: The changes within local tumour microenvironment of GBM cells, including hypoxia also may induce the enhanced expression of HIF-1α, HIF-2α and stem cell-like markers such as pluripotency-associated gene products Oct-3/4, Sox-2, Nanog and Myc that promote their stem cell-like properties and gain of a more aggressive behaviour [126, 127, 145, 146].