FGF2 and glioblastoma: To investigate as to whether GF-independent GSCs (I-GSCs) might embody an intrinsic component of the tumor itself, acutely isolated cells from IDH1-wild-type GBM specimen were plated at clonal density in serum-free medium, either in the presence of EGF and FGF2 [14, 49] or avoiding the classical mitogenic stimulation.