Fig. 1.

Characterization of tumor spheres. U87 human gliomas form spheres in culture under adherent conditions (arrows) (a), when grown for 7 days on soft agar in medium with 5% fetal bovine serum (b) and when grown on NSC medium (c). Spheres grown on soft agar and adhered cells, obtained from subconfluent cultures which did not contain spheres, were analyzed by western blotting with anti-CD133 (d) and RT-PCR for markers of undifferentiated (Oct-4) and differentiated cells (GLAST and CaMKII) (e). LC loading control. Bar size = 100 μm. Proportion of Oct-4 and Nanog-positive cells was evaluated by flow cytometry in U87 (n = 3) and U343 (n = 2) human gliomas grown on 5% FBS and on NSC medium. Paired experiments are linked by lines. Average ± SEM are shown as small lines (f)