**3.1. Cell lines and cell culture**

The glioma cell line #12537-GB has been previously described [6]. The #12794-GB cell line has been established from a female patient's tumor material received from the neurosurgical department of the Bezirkskrankenhaus in Günzburg (Universal trial number: U111-1179-3127) with patient-informed consent. The tumor material was minced and cells from the tumor material were taken into the culture by trypsinization of the tumor material (2.5% trypsin), followed by Ficoll separation. Continuous cultures were performed in Iscove's Modified Dulbecco's Medium (IMDM) (Lonza.com, USA) supplemented with 10% fetal calf serum (FCS, endotoxinfree, Batch 0247x, Merck/Biochrom.com, Germany), GlutaMAX (ThermoFisher.com, USA), and antibiotics at 37°C under 5% CO2 . Hs68 fibroblasts (Hs68-Fi) were purchased from ATCC, and cultured in IMDM containing 10% endotoxin-free FCS (Batch No: 0247x, Merck/Biochrom.com).
