CD8A and neoplasm: The DN and CD8+ tumor populations differ in their ability to disseminate outside the thymus, since we could only find peripheral cancer cells at high frequency (45% of cases, n = 45) in CD8+ tumor-bearing animals (Figures 1C, S1E, and S1F). Similar immunophenotype distributions were observed in tumors from N-nitroso-N-methylurea- and urethane-treated Vav1−/− mice (data not shown).