This finding suggested that Tregs and Teffs expressing TCR of the same specificity could at least in part arise by conversion from CD4+Foxp3− T cells or that Tregs were derived from separate precursors or that many tumor-reactive clones pre-exist in normal repertoire, often at relatively high frequency, and that their TCRs do not exclusively drive these cells differentiation to only effector or regulatory lineages. Here, CD4 is linked to neoplasm.