U87R cell line is radioresistant.

(A, B) U87R cells has more foci number than U87 cells. Indicated cells were exposed to several radiation dose and the experiments were repeated three times. The numbers of foci formation were presented as bar graphs. *p<0.05, **p<0.01. (C) U87R cells have more foci fraction than U87 cells. Foci fractions were calculated by dividing the number of colonies formed after radiation by the corresponding number of colonies formed without radiation from experiments in (A and B). (D) U87R cells get less effect than U87 cells from radiation on growth pattern. U87R and U87 cells plated in 96-well culture plates were exposed to radiation with 3 Gy cell growth was monitored by measuring cell numbers with MTS assay. **p<0.01.