ID1 and glioma: Many genes were downregulated in the co-culture including VEGFR1, NOTCH4, FGF1, FGF2, TGFβR1 and MMPs (p < 0.001), with a few genes upregulated significantly including CXCL1 and ID1 (Figure 2H and Supplementary Table 4), indicating an overall dampening of the glioma-derived angiogenic response in the presence of canonical brain endothelial cells.