VEGFA and glioblastoma: Firstly, the vascularization of GBM is not only related to the angiogenic process triggered by the main axis of hypoxia/hypoxia response element (HRE) sequence transcription/VEGF activation, but also by many types of vessel-generation processes, which can be distinguished into five types: (i) angiogenesis; (ii) vasculogenesis; (iii) vascular co-option; (iv) vascular mimicry; and (v) glioblastoma-endothelial-cell transdifferentiation [73].