CD248 and glioblastoma: Evidence for the criticality of endosialin expression in tumor growth and progression comes from the findings in glioblastoma cells and placental fibroblasts that endosialin expression is upregulated by hypoxia inducible factor-2 (HIF-2) [39], produced as a result of rapid proliferation of tumor cells generating areas of hypoxia leading to the expression of HIF-1 and HIF-2, upregulated gene expression, and vascular remodeling.