Figure 1. Glioma specific molecular alterations are not a common feature of endothelial tumor vasculature in clinical samples.

(a) PDGFRA amplification in tumor cells (arrow) but not in endothelial cells (arrowheads) in adjacent vessel (V). (b and c) Molecular alterations in neoplastic cells by immunohistochemistry, but not in vasculature (V), including EGFR overexpression (b) and PTEN loss (c). Quantification of vessels in tumors stained for IDH1 R132H mutant protein by immunohistochemistry (d-f) or EGFR amplification by CISH (g-i) revealed that most tumor cells showed positive staining, whereas the vessels (V) were devoid of signal (d and g). Tumor cells were found to crowd the perivascular region (e and h), but only rare vessels contained positive cells within the vascular wall (f and i).