Figure 2.

Factors that enhance short-term radiosensitization and correlation with apoptosis and premature senescence frequencies. A) Examples of enhanced SRF_2Gy when IR is repeated (2 Gy × 2, 24 hours apart) or when incubation times are extended to 6 days (incubation times counted from day of (first) irradiation). Data points shown represent mean (+/− standard error) based on at least three biological repeat experiments. Statistical comparisons by unpaired T-test, two-sided. B) Correlation of SRF_2Gy values with relative change in the percentage of Annexin V positive cells upon adding drug to IR, normalized for drug alone effect. Data points represent differences between drug + 2 Gy versus 2 Gy alone effects in several cell lines, except for square symbol which indicates a 2 × 2 Gy treatment. Solid line, result of linear regression analysis. C) Analogous to panel B, correlation of SRF_2Gy with relative change of SA-β-gal positive cells scored 3 days after irradiation, except for square symbol which re-presents a 6-day experiment.