Apoptosis induction: nuclei fragmentation and caspase 3 activation. T98G cells were incubated with TAZnPc or ZnPc dissolved in DMEM supplemented with 4% FBS plus antibiotics at a concentration of 0.5 µM during 18 hours. Then the medium was replaced and the cells irradiated using two light doses: 10 J/cm2 or 27 J/cm2. Cells were fixed at different times post PDT and activation of caspase 3 and nuclei fragmentation were monitored using anti-CC3 antibody and DAPI staining respectively, as described under Materials and Methods. (a) Representative photomicrographs of T98G cells without Pc (first row), with TAZnPc (second row) or with ZnPc (third row), non-irradiated (first column) or irradiated using 10 J/cm2 (second column) or 27 J/cm2 (third column) stained using anti-CC3 antibody (red) and DAPI (blue). Magnifications of boxed areas are shown (I-IV, fourth row). (b) Quantification of apoptotic cells (CC3+ cells with fragmented nuclei) represented as mean % ± SD of apoptotic nuclei over the total number of nuclei (DAPI positive). ***p < 0.001 with respect to the control using two way ANOVA with Tukey’s post-test.