The human glioma cell lines, LN229 and A172, were obtained from ATCC (Manassas, VA). U251HF glioma cells were kindly provided by Dr. W. K. Alfred Yung (M. D. Anderson Cancer Center, Houston, TX); U251HF-Luc were generated by stably transfecting a firefly luciferase gene under a CMV promoter into U251HF cells and maintained as described with the addition of Geneticin (G418–800μg/ml) for U251HF-Luc cells (23 (link)). GSC2, GSC20, GSC11, GSC23 and GSC811 patient-derived glioma stem cell lines (24 (link)) were kindly provided by Dr. Frederick Lang (M. D. Anderson Cancer Center, Houston, TX) and cultured as neurospheres passaged every 5–7 days in serum-free DMEM/F12 medium containing B-27 Supplement (Life Technologies, Carlsbad, CA), bFGF (FGF2 Gold BioTechnology, St. Luis, MO) and EGF (Gold Bio Technology). Cell lines were authenticated at the University of Arizona Genetics Core (http://uagc.arl.arizona.edu/services/cell-line-authentication-human). Onalespib (AT13387) was purchased from Medkoo Biosciences (Morrisville, NC).