Figure 1

Bioluminescence expression is proportional to the number of tumor cells in spheroids formation. A: eGFP expressing glioma spheroids initiated from an increasing number of 172 glioma cells (500, 1000, 2000, 4000, 8000, 16000, 32000, 64000, 96000, 128000) per well. B and C: Bioluminescence measurements for increasing cell numbers of U251 and A172 glioma cells demonstrated a linear relationship (R² = 0.9993 for U251 cells and R² = 0.9987 for A172 cells).