Unexpectedly, BCRP staining was positive in CD31+ blood vessels in s.c. pHGG xenografts (Figure 5F and S6A), while it was negative in all the PDX models derived from extra-CNS cancers, suggesting that pHGG cells, but not other cancers, favor the expression of BBB markers in the vasculature of the microenvironment (Figure 5F). The gene discussed is PECAM1; the disease is cancer.