We chose an orthotopic U251 tumor model for these studies because in our experience, and in the experience of other labs, this model recapitulates many of the key features of clinical GBM, including rapid growth, necrosis, hypoxia, increased VEGF expression, and invasive growth [33-37], although we acknowledge that any implantable mouse model for GBM has inherent limitations. The gene discussed is VEGFA; the disease is neoplasm.