Figure 3: Cell viability of U-87 MG glioma cells (presented as a percentage of the blank control) following: (a) ALA ± CP94 PDT-treatment, (b) MAL ± CP94 PDT-treatment and (c) HAL ± CP94 PDT-treatment. Data represents the mean of 5 wells ± 1 standard deviation, carried out in triplicate (n=3). *represents a significant difference in cell viability between cells subjected to 20% oxygen compared to cells subjected to 5 or 40% oxygen (p<0.05).