Increased survival of 32D cl 3 cells with elevated mitochondrial SOD activity. Cells from 32D cl 3, 32D-Cu/ZnSOD, 32D-MnSOD, 32D-MnSOD-ML, and 32D-ML-Cu/ZnSOD were irradiated with doses ranging from 0 to 8 Gy. The cells were plated in 4% methylcellulose and colonies of > 50 cells were counted 7 days later. The data were analyzed using linear-quadratic and single-hit, multitarget models. 32D-MnSOD and 32D-ML-Cu/ZnSOD cells having increased mitochondrial SOD activity were more resistant to radiation [D0 = 2.10 ± 0.10 (P = 0.001) and 1.97 ± 0.17 (P = 0.0127) Gy, respectively] than 32D cl 3, 32D-Cu/ZnSOD, or 32D-MnSOD-ML cells (D0 = 1.15 ± 0.11, 0.89 ± 0.01, and 1.08 ± 0.02 Gy, respectively) (P < 0.195 and P < 0.673). Results are presented as the means ± SEM with an n of 3. P values were determined using a Student’s t test. *Represents a statistically significant difference from 32D cl 3 cells. (Reproduced from M.W. Epperly et al., Radiat Res 160 (2003) 568–78, with permission of the publisher.)