Specifically, while CSCs enriched tumor spheres are cultured in serum-free medium supplemented with fibroblast growth factor (i.e., DMEM-F12/ B27 plus bFGF), the floating spheroids of PDAC cells described in this study are cultured in serum-containing medium (RPMI +10% FBS) without addition of any specific cytokines/growth factors. The gene discussed is FGF2; the disease is neoplasm.