FOXP3 and neoplasm: 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.