Moreover, oligosaccharides distributed to the mitochondria in C2C12 cells and increased the expression of PGC-1a, which suggested that the actions of these oligosaccharides might be associated with mitochondria. Furthermore, introduction of Chromium to the marine oligosaccharide increased its bioactivity to some extent. Therefore the oligomannuronate-chromium complex could be considered a potential agent in the treatment of type 2 diabetes due to its activation of PI3K/Akt and AMPK. This is the first report to suggest a possible mechanism by which the oligomannuronate-chromium complex improves insulin sensitivity. We conclude that the oligomannuronate-chromium complex might provide the basis for an adjuvant therapy of type 2 diabetes by enhancing insulin sensitivity with a lower toxicity profile than that of metformin. Regulatory T cells are a subgroup of CD4+ T cells characterized by expression of CD25 and a key transcription factor, known as forkhead box P3. They can suppress the activation, proliferation and effector functions of various immune cells in vitro and in vivo. This unique ability makes Tregs central in the prevention of autoimmune disease and maintenance of allograft tolerance. However, as a double-edged sword, Tregs can also suppress anti-cancer immune responses and favor tumor progression. Thus, the relation of Tregs to carcinogenesis has become a field of intense investigation recently. Emerging evidences demonstrate Tregs also play a central role in the immunopathogenesis of cancers. First, a higher frequency of Tregs in both peripheral blood and LEE011 tumors was reported in patients with a variety of cancers. This list continues to grow following the current interest of studying Tregs in human tumors. Second, the number of tumor-infiltrating Tregs is negatively associated with patient prognosis. Third, it has been established that in murine models, selective depletion of Tregs can induce regression of established tumors. Overall, Treg-cell-mediated immunosuppression is one of the crucial tumor immune-evasion mechanisms and the main obstacle of successful tumor immunotherapy. Hepatocellular carcinoma is the fifth most common cancer worldwide with a poor prognosis and limited survival in the majority of patients. Nowadays, Tregs are being extensively studied in human HCC. Increased number of Tregs has been reported in peripheral blood and, particularly, tumor tissues of patients with HCC. Furthermore, the main mechanisms by which Tregs facilitate liver carcinogenesis are to prevent CD8+ T cells from proliferating in response to tumorassociated antigens and from becoming cytotoxic effector cells. However, little is known about the mechanisms leading to the increased Tregs in tumor tissue. It is summarized that there are four mechanisms responsible for this, and the recruitment of Tregs is the most important approach. The migration of lymphocytes to the target site was a multi-step procedure, in which signals from chemokines/chemokine receptors play a critical role.