Furthermore, Xlf−/−Trp53−/− double Knock-Out (DKO) mice do not develop Pro-B cell lymphomas commonly seen in other NHEJ-Trp53 DKO conditions (22), further attesting for the absence of a major V(D)J recombination defect in these mice, and the thymic cellularity is even partly rescued in the Trp53−/− background (24). This evidence concerns the gene NHEJ1 and B-cell non-Hodgkin lymphoma.