HIF1A and meningioma: HIF-1α-positive expression in meningioma PTBE grades 0, I, II, and III was 34.4% (22/64), 47.1% (16/34), 54.5% (18/33), and 75.9% (22/29), respectively (Bonferroni-corrected, P = 0.003, α/6 = 0.008).