VEGFA and neoplasm: The brain-tumor-barrier (BTB) appears at the level of the tumoral core, where the BBB is partially disrupted, causing increased permeability, VEGF overexpression with increased angiogenesis in the hypoxic zones, and the release of cytokines and chemical mediators that lead to the formation of new immature and permeable vessels within the tumor [53,54,55,56,57].