While it is not only endothelial cells that constitute the cellular substrate of microvascular proliferation [11,12,13], recent reports have shown that CD276 (B7-H3), an immune checkpoint marker of prognostic significance [14,15,16], is strongly expressed by abnormal endothelial cells in various cancers including glioblastoma (Figure S1) [14,17,18,19]. The gene discussed is CD276; the disease is glioblastoma.