PTPRC and glioblastoma: For comparison, expression of KDR/VEGFR-2, an angiogenic marker expressed by endothelial cells; CD11b, a monocyte/macrophage marker; and CD45, a pan-leukocyte marker were determined by immunohistochemistry on sequential frozen sections of a glioblastoma used for the in situ hybridization (Fig 5).