OLIG2 and glioma: Based on the observation that the vast majority of glioma cells in our mouse model are of OPC/NPC character, expressing Olig2, and that these cells tend to invade the brain by single-cell vessel-cooption50, we performed an immunostaining analysis and quantified the number of OLIG2+ cells related to endothelial cells at the invasive rim of mouse tumor-brain tissue sections.