PECAM1 and brain neoplasm: In the present study, we explored the spatial and amount distribution of the P-gp as a drug efflux pump expressed on tumor and ECs plasma membranes [27], mitochondria as an indicator of increased cell activity and proliferation [40], S100A10 as a specific biomarker of glioma cells [33,34,41], and CD31 as ECs marker [42] across different brain tumors: human meningioma, IDH-mutant astrocytoma, and IDH-WT glioblastoma.