GFAP and central nervous system cancer: Bmi1 downregulation induced cell differentiation associated with morphological changes and decreased expression of the stem cell-related proteins Nestin and Sox2, accompanying induction of an astrocytic fate in U373 glioma cell line, determined by increased levels of the astrocyte-specific marker GFAP, and decreased levels of oligodendrocyte-specific marker CNPase (Figures 2A–D and S2B).