TP53 and mature T-cell and NK-cell non-Hodgkin lymphoma: The fact that p53 was downregulated in thymocytes isolated from 9 month old, but not 6 week old, Dnmt3a+/- tumor-free mice indicates that p53 downregulation is chronologically an intermediate event in lymphomagenesis and this strongly suggest that this event is relevant in the initiation/progression of CD8+ PTCL.