EGF and glioblastoma: These include (i) genetic activation of oncogenes in normal organoids (8, 13); (ii) invasion of normal iPSC-derived brain organoids by GSCs (9, 12); (iii) GBM organoids derived from fresh pieces of GBM, which include stromal vessels and immune cells (GBO) (10); (iv) GSC-derived GBM organoids plus Epidermal Growth Factor/Fibroblast Growth Factor (EGF/FGF) (11); and (v) our feeder-free GBMO system.