Figure 5

Reduction of apoptosis improved the estimation of DNA repair in NP18 xenografts. PFGE was performed in unirradiated (black bars) and irradiated (45 Gy; white bars) cell-plugs obtained from xenografts (NP18) incubated in absence or presence of zvd-fmk (10 μM). Optical density was normalized to radiation-induced initial damage in absence of, or presence of zvd-fmk. In absence of zvd-fmk, spontaneous DNA fragmentation (black bars) increased significantly while radiation-induced breakage (white bars) decreased over time-course. In presence of zvd-fmk, radiation-induced fragmentation decreased but spontaneous DNA breakage was blocked. *P < 0.05 compared to optical density at time 0 h (Mann-Whitney test, 4 independent experiments).