Tumor cells continue to proliferate following sub-lethal doses of radiation.

<p>Proliferation was measured 72 h after receiving 0, 2.5, 5, or 10 Gy of radiation by measuring BRDU incorporation. Cells receiving 25 or 30 Gy of irradiation were used as a positive control for inhibition of proliferation. A. Proliferation of SW620 cells. B. Proliferation of WiDr cells. C. Proliferation of HCT116 cells. Samples were done in triplicate at each dose. Experiment was repeated 3 times with similar results.