Professor Joyce Taylor-Papadimitriou is Principal Scientist and Joint Head of the ICRF Breast Cancer Biology Group at Guy’s Hospital. She is distinguished by her work defining the phenotypes of the malignant cell in breast cancer. In particular, she identified and characterised a tumour associated antigen (the MUC1 membrane mucin) as being a component of normal glandular epithelial cells that is over-expressed and aberrantly glycosylated in breast and other cancers such as ovarian cancer. This discovery has had a major impact in clinical oncology and glycobiology. The first antibody to the mucin which she developed has been shown in a Phase 1/11 trial to improve survival of ovarian cancer patients, and is being evaluated in a large randomised Phase 11 Trial. Immunogens based on the MUC1 mucin are also in clinical trial.