U251 cells (a), GBM PDX1 cells (b) and PDX2 cells (c) were virally infected with Nestin shRNA (shNes) or scrambled shRNA (shCtrl). At 96 hrs following the infection, cells were treated with etoposide (1 μM, 5 μM, 10 μM, 25 μM, 50 μM, 100 μM), vinblastine (1.5 nM, 3 nM, 5 nM, 10 nM, 20 nM) or vincristine (0.2 nM, 1.2 nM, 2.5 nM, 5 nM, 10 nM, 50 nM) for 48 hrs. The cell viability was measured by CCK8 assay, and plotted against the concentrations. IC50 of vinblastine and etoposide in GBM cells was quantified. Drug responses of Nestin deficient cells and control cells were compared by Log-rank test.