TP53 and neoplasm: Summary of histological analysis. Tissues of 17 control and 20 Rapatar-treated p53−/− mice were evaluated for the presence of tumor cells. The type of tumors and the stage of their development were determined as described in Materials and Methods. The incidence of sarcomas in Rapatar-treated p53−/− mice was higher than in control group (30% and 17% respectively); however, due to a relatively small group size, statistical significance was not achieved (p=0.2; Fisher's exact test)