ASPM expression in gliomaspheres increases with successive passages in vitro and in vivo. (a) Metaphase staining of ASPM protein at both poles of the spindle. ASPM protein (green) is detected in gliomaspheres (arrow). Nuclei are stained with DAPI (blue); (b) ASPM expression increases with successive passages (p) in gliomaspheres issued from GBM 1, 2 and 3. Passages were performed in vitro every 8 to 12 days; (c) GBM1 cells were subcutaneously engrafted into nude mice and Aspm expression was measured over four passages. Aspm expression increased progressively in xenograft tumor (mean +/- SEM; n = 3 to 5 mice for each point. In vivo passages were performed every 8-16 weeks.