Specifically, the presence of perivascular stromal cells significantly increased the number of tumor cells within 50 μm of the resulting microvascular network—where 50 μm has been used in prior literature to define the perivascular niche environment.[9, 18] While a majority (>70%) of tumor cells expressed SOX2 regardless of the complexity of the perivascular network, we observed reduced SOX2 expression in GBM6 cells in perivascular cultures that included astrocytes versus those derived only with ECs (Figure 4B,C). The gene discussed is SOX2; the disease is neoplasm.