4.1. Cell Cultures and Growth Conditions

GBM22, GBM123, GBM14, and GBM12 were obtained from the Mayo Clinic Brain Tumor Patient-Derived Xenograft National Resource (Mayo Clinic, Rochester, MN, USA). U251 cell line was obtained from Sigma (St. Louis, MO, USA). U87 and LN229 were purchased from the American Type Culture Collection (Manassas, VA, USA). KNS42 was purchased from Riken BioResource Research Center (Ibaraki, Japan). Cells were cultured in DMEM medium (Fisher Scientific (Waltham, MA, USA), MT10013CV) containing 10% FBS (Gemini, NY, USA, FBS002) and 100 μg/mL of primocin (Invivogen, CA, USA, ant-pm-1). For the experimental conditions, cells were cultured in DMEM containing 1.5% FBS and primocin. NCH644 stem-like glioma cells were obtained from Cell Line Services (CLS, Heidelberg, Germany) and were cultured in GBM-MG from Cell Line Services (CLS, Heidelberg, Germany, 820403) for both maintenance and experiments. All cell lines were incubated at 37 °C in an atmosphere containing 5% CO₂.