We find that GBM induced in neural stem-cell-like glial fibrillary acidic protein (GFAP)-expressing cells in the subventricular zone of adult mice shows accelerated tumor development and produces more malignant GCs (mGC1<sub>GFAP</sub>) that are less resistant to cancer drugs, compared with those originating from more differentiated nestin- (mGC2<sub>NES</sub>) or 2,'3'-cyclic nucleotide 3'-phosphodiesterase (mGC3<sub>CNP</sub>)-expressing cells.