IL21 and liver cancer: These observations indicated that pGM-CSF-GFP-IRES-Rae-1-IL-21 significantly inhibited the growth of liver tumors by lowering the Treg frequency, increasing immune modulation, frequency and cytotoxic activities of immune cells like CTL and NK cells, enhancing Rae-1 expression in liver cancer tissues, and facilitating the recognition of tumor cells by CTL and NK cells and debulking liver cancer.