Differential response of the GBM CSC to GSI-X and AG1478 treatment. (A) GSI-X negatively affect cell proliferation of GBM c-CSC pools after 3 and 5 days of treatment as compared to p-CSC pools by MTS assay. (B) GBM CSC proliferation decrease after 2 days by single EGFR inhibition. Concurrent EGFR and Notch1 inhibition results in a synergistic anti-proliferative effect in c-CSC2 and c-CSC3 pools as compared to relative p-CSC pools. Error bars represent the mean ± SD (n = 3). All data shown are representative of results obtained from experiments conducted three times.