Figure 10.

Percentage of viability at 24 h postillumination for U87. NT, nontreated; 5-ALA, photosensitizer only (0.2, 0.6,or 1 mM); light, illumination for 5, 10, 20, 30, and 40 min; PDT, illumination in the presence of 5-ALA for 5, 10, 20, 30, and 40 min. Results are presented as means of three independent experiments, expressed in % of the NT. Linear regression was performed, all quoted p-values are two-sided, with p ≤ 0.0001 (***) and p ≤ 0.001 (**) considered statistically significant, and p ≥ 0.05 considered not significant (NS).