PECAM1 and glioblastoma: As well explained elsewhere [37], here, we employ double immunohistochemical stainings for CD31, P-gp, S100A10, and mitochondria (as a marker of active aerobic metabolism) on formalin-fixed, paraffin-embedded human samples of IDH-WT glioblastoma, IDH-mutant astrocytoma, and meningioma to study vascular co-option using the Aperio colocalization algorithm (Leica Biosystems, Nussloch, Germany), which is a valid and robust method to handle and investigate large data sets.