Fig. 1.

Demonstration of very low radiation dose induced adaptive responses in two mouse tumor cell lines differing in p53 mutational status. P values were determined by comparing the survival of cells following two 2 Gy doses with those exposed to two 2 Gy doses along with the 5 mGy doses using a Student’s two-tailed t-test with values ≤0.05 identified as significant. Exposure to 5 mGy induced a significant elevation in SA-NH p53 WT (P=0.001) and reduction in FSa p53 Mut (P<0.003) cell survival. The presence of NAC during the 5 mGy irradiation inhibited these effects in both SA-NH (P=0.572) and FSa (P=0.841). Each experiment was repeated three times and error bars represent the standard error of the mean (SEM).