HIF1A and glioma: The activation of ERK1/2 by thyroid hormone within 30 minutes elicits proliferation of glioma cells while PI3K activation increases the expression of hypoxia-inducible factor-1α (HIF-1α), as it comes from the activation of two different sites, S1 for HIF-1α transcription and S2 for cell proliferation on the integrin molecule (20, 66).