The human long-term cell lines (LTC) (LN-18, LN-428, D247MG, LN-319, A172, U87MG, T98G, LN-308, LN-229) and human glioma-initiating cell lines (GIC) (T-325, T-269, ZH-161, S-24, ZH-305),17,18 LN-428, ZH-161 and ZH-305 cells with lentiviral cmet gene silencing,19 LN-229 cells with O6-methylguanine DNA methyltransferase (MGMT) overexpression,20 and LN-18 and LN-229 cells with acquired resistance to TMZ21 have been described. LTC were cultured in Dulbecco’s modi fied Eagle’s medium supplemented with 10% fetal calf serum and 1% glutamine (10 μL/mL) (Invitrogen, Basel, Switzerland). GIC were isolated after obtaining informed consent and approval of the local ethics committee from freshly resected tumors using the Papain Dissociation System (Worthington Biochemical Corporation, Lakewood, NJ). Briefly, tumor tissue was minced and tissue was digested in DNase/Papain mixture (vial #2 and #3) for 30 min at 37 C. After incubation, the tissue was filteredtwice through a 70 μm mesh and washed with phosphatebuffered saline. Cells were centrifuged, the supernatant was removed and the pellet was separated into cells and membrane fragments by using a gradient consisting of sterile Earle’s Balanced Salt Solution/inhibitor solution mix (vial #1 and vial #3) and albumin inhibitor (vial #4). Cells were resuspended in phenol red-free complete Neurobasal Medium (NB) with B-27 supplement (20 μL/mL) (Thermo Fisher Scientific, Waltham, MA), L-glutamine (10 μL/mL), fibroblast growth factor-2 and epidermal growth factor (20 ng/mL each; Peprotech, Rocky Hill, PA) and penicillin/streptomycin (pen-strep, Sigma-Aldrich/Merck, Darmstadt, Germany) and cultured overnight. The next day medium was exchanged and cells were cultured in phenol red-free complete NB. All cells were sent for short tandem repeat analysis (DSMZ, Braunschweig, Germany) and are regularly tested for mycoplasma contamination.