Only one cell line–HROG36 –showed results that were relatively consistent with the hypothesis of loss of cell hierarchy and conversion of non-CSCs into CSCs in our study: 1) increased tumorigenicity after treatment with TMZ that was associated with a higher mitochondria content, 2) diminished tumorigenicity and lowered mitochondria content after Dox treatment and 3) higher expression of both analyzed GBM CSC markers nestin and CD15 after TMZ treatment but not after Dox or combination treatment. Here, NES is linked to glioblastoma.