However, expression levels of angiogenic markers, including hypoxia-inducible factor 1α (HIF-1α), HIF2α, vascular endothelial growth factor (VEGF), VEGF receptor 1 (VEGFR1), and VEGFR2, usually cannot reliably predict GBM prognosis or therapeutic outcomes, possibly due to the rapid turnover of angiogenic proteins [17]. Here, FLT1 is linked to glioblastoma.