FOXP3 and neoplasm: Many more studies have since confirmed that ‘suppressor’ T cells, subsequently defined as CD4+ CD25hi Foxp3+ regulatory T (Treg) cells are often enriched within tumour sites where they may inhibit the activity of anti‐tumour T cells and promote tumour progression.6 Several suppressive mechanisms used by Treg cells have been reported, all of which may contribute to the immunosuppressive tumour microenvironment, allowing the cancer to progress (reviewed in ref. 7).