Human HEK293T cells purchased from the ATCC, and stat3-null HeLa cells purchased from ABclonal (20170728-02) were grown in Dulbecco's modified Eagle’s medium (DMEM) with 10% fetal bovine serum (FBS; FND500, excellbio), 100 U/ml penicillin and 100 U/ml streptomycin. GSC lines were obtained from Professor Jeremy N. Rich (University of California San Diego). GSCs were cultured in Neurobasal™ medium (12348017, Gibco) supplied with B27 supplement (12587010, Gibco), 10 ng/ml epidermal growth factor (EGF) and 10 ng/ml fibroblast growth factor (FGF) as previously described (17 (link),18 (link)). All cell lines were used for a limited number of passages and checked for Mycoplasma infection.