Figure 4.

Hyperoxia and Combination Exposure Induces Cell Cycle Arrest. Non-tumorigenic murine alveolar type II epithelial cells (C10) were evaluated after 1 and 2 cycles of hyperoxia and radiation exposure and evaluated by flow cytometry for DNA content. (a,b) Cell cycle histograms display the DNA content (diploid or 2N; tetraploid or 4N) after 2 cycles (48 h) of exposure and (c) data are expressed as the ratio of G2 to G1. Data are presented as mean ± SEM. * p < 0.05 for each exposure condition as it compares with the unexposed control (CTL) in the same respective time-group; ^# p < 0.05 for significant differences between O₂-alone compared to O₂ + IR; ^§ p < 0.05 for significant differences between IR-alone compared to O₂ + IR.