To analyze whether the JAK3 inhibitors WHI-P131 and PF-956980 could affect the stemness of GBM cells and their ability to form spheres, we treated U87 and U251 cells with the inhibitors and cultured them in a proliferation medium devoid of serum but containing epidermal growth factor (EGF) and basic fibroblast growth factor (FGF). Here, EGF is linked to glioblastoma.