The long-standing interests of our laboratory center on identifying specific mechanisms of human anti-tumor immunity and cancer immunosurveillance. We study T cell and antibody repertoire in cancer patients and in healthy individuals at risk for cancer and factors that influence that repertoire. We were the first to identify a human tumor antigen recognized by human T cells and antibodies, the epithelial mucin MUC1. We showed that tumors express an abnormal form of MUC1 that is recognized by the immune system as a foreign rather than a self-antigen. Studies in mice and primates showed that MUC1 was immunogenic and that anti-MUC1 immune responses can reject tumors. These studies supported multiple clinical trials of a MUC1 vaccine in patients with breast, colon and pancreatic cancer. Most recently, we began testing a MUC1 vaccine for cancer prevention in individuals diagnosed with MUC1+ premalignant lesions. In addition to being a tumor antigen, MUC1 is an oncogene by virtue of promoting a highly inflammatory tumor microenvironment. We discovered that the tumor form of MUC1 activates NF-kB, binds p65 and translocates to the tumor cell nucleus where it binds to and activates promoters of inflammatory cytokines, such as IL-6 and TNF-a. MUC1 has been associated with a more invasive cancer phenotype and we have recently deciphered the mechanism by showing that it forms complexes with CIN-85, also previously associated with cell motility and invasion.