Fig. 5.

The effect of p53 siRNA transfection on the expression of the survivin-associated adaptive response in SA-NH tumor cells. The cell survival of untransformed (UT) and mock transformed (MT) SA-NH control cells were contrasted to negative control (NC) and p53 siRNA transfected cells following two 2 Gy doses separated by 24 h and 5 mGy administered 15 min prior to each of two 2 Gy doses. P values were determined by comparing the surviving fractions of the two 2 Gy treatment with that of the 5 mGy+ 2 Gy exposures × 2 of nontransfected and p53 siRNA transfected SA-NH. 5 mGy induced a cytoprotective adaptive response in nontransfected cells (P < 0.001) and a sensitizing response in p53 siRNA transfected SA-NH cells (P = 0.003). Experiments were repeated three times and error bars represent the SEM.