CD133+ cells are maintained in culture for a long time without losing their ability to reproduce the parental human phenotype: CCSCs, after enzymatic digestion, can be expanded as tumor spheroids in vitro with a serum-free medium complemented with epidermal growth factor (EGF) and basic fibroblast growth factor (bFGF), using low adhesion conditions (to induce differentiated cells death due to the anoikis) [86]. This evidence concerns the gene FGF2 and neoplasm.