Having established that continuous administration of Mdm2i inhibited growth of p53 wild-type tumors in the absence of radiation (Fig. 3f) and that following irradiation Mdm2i could sustain p53 levels and activity with a single dose (Fig. 4a, b), we next tested whether a single dose of Mdm2i shortly after radiation (2 h) could control tumor growth. The gene discussed is TP53; the disease is neoplasm.