TP53 and neoplasm: In order to understand what leads to catastrophic events in the precursor cells, we analyzed the cerebellum from early postnatal stages up to tumor onset in age-matched Nestin-Cre p53−/−Xrcc4c/c, Nestin-Cre p53−/−Xrcc4c/+ and Nestin-Cre p53−/−Xrcc4c/− animals (Fig. 3).