Before tumor onset, these ALK+ cells were either CD4+ or CD8+ T cells (i.e., TCRβ+), whereas in tumor-bearing mice, additional CD4−CD8−TCRβ− tumor cells were detectable, suggesting that a fraction of ALK-transformed DN tumor cells was able to leave the thymus, or that the TCR expression is silenced after exit from the thymus as suggested previously (45) (Fig S2B). The gene discussed is ALK; the disease is neoplasm.