EGF and neoplasm: Since monolayer tumor cells maintained in traditional fetal bovine serum (FBS)‐based media do not share biological features with neurospheres propagated in serum‐free media (supplemented with EGF and βFGF), which favors the growth of cancer stem cells,[15, 30, 35, 36] we incubated pGBM cells in both types of growth media to have a better coverage of cell subpopulations and to understand the differences between the monolayer and the neurosphere cells.