CD4 and neoplasm: Conversely, BCL6 can also preserve the ability of Treg cells to restrict effector T cell function in the tumor microenvironment, with enhanced Treg expression of BCL6 correlating with poor prognosis in colorectal cancer and melanoma lymph node metastasis [130], while BCL6 has also been shown to suppress the infiltration of CD4+ T cells to promote hepatocellular carcinoma development [131].