FOXP3 is a transcription factor necessary and sufficient for induction of the immunosuppressive functions in regulatory T lymphocytes. Its expression was first considered as specific of this cell type, but recent data indicate that FOXP3 is also expressed in human tumor cells, with a variety of different tumors including pancreatic adenocarcinoma, breast cancer, gastric cancer, ovarian cancer and adult T-cell leukemia/lymphoma (ATLL). In addition the FOXP3 expression in tumor cells is associated with a less favorable prognosis and others studies presented evidences that support the role of FOXP3 up-regulation as anti-tumor and ante-metastatic mechanisms.