The role of hypoxia-inducible factor-1 (HIF-1), a transcription factor implicated in tumorigenesis and tumor neoangiogenesis, in PTBE formation was also investigated, and it has been shown how, under hypoxic conditions, overexpression of HIF-1 leads to BBB disruption and PTBE formation in meningiomas [51]. This evidence concerns the gene HIF1A and meningioma.