(A) Simulation of the p53 response to γ-irradiation in cells treated with: (i) control RNAi, (ii) lower efficiency Wip1 RNAi and (iii) higher efficiency Wip1 RNAi, with concomitant increase in Mdm2 production. Values for the Wip1 production rate βi (Cs h−1), the p53-independent Mdm2 production rate βmi (Cs h−1), the initial active p53 concentration p53active0 (Cs), and the initial Mdm2 concentration Mdm20 (Cs)] were (i) [0.25, 0.2, 0, 0.2], (ii) [0.2125,0.35, 0.1, 0.35], and (iii) [0.175, 0.5, 0.2, 0.5]. All other parameter values were as indicated in Table S1. (B) Immunoblots of Wip1, p53, Mdm2, and tubulin in MCF7 cells transfected with control or Wip1 siRNA 72h prior to harvesting. Blots are representative of triplicate experiments.