In a previous study, we isolated Ad-GSCs and Sp-GSCs from the GBM6 PDX, and showed that both populations had high expression of stem cell markers, such as CD133, Sox2 and Nestin, but low expression of differentiation markers such as βIII-tubulin and glial fibrillary acid protein as compared to bulk tumor cells [25]. This evidence concerns the gene NES and neoplasm.