Fig. 1

A549R and H1299R cells were more resistant to ionizing radiation than the parental A549 and H1299 cells. a The cells were irradiated with the indicated dose; 48 h later, Cell Counting Kit-8 assay was performed to detect the viability and proliferation of the cells. The survival rate was normalized to the non-irradiated controls. *P < 0.05 (Student’s t test). b The cells were irradiated with 2 Gy of X-ray; 24 h later, the apoptosis of the cells was determined by Annexin V-FITC/propidium iodide (PI) staining and fluorescence-activated cell sorting analysis. Representative results are shown. The apoptotic fraction (Q2 + Q4) from three independent experiments was used to plot the bar chart. *P < 0.05 (Student’s t test)