MUC5AC and cancer: Mucin glycoproteins in cancer show modifications, both in mucin expression and their O-glycosylation profile.165 For example, epithelial cancer cells and early epithelial premalignant lesions are known to express immature truncated glycans.166 Cancer biomarker assays usually centre around detection of changes in expression and bio-distribution of products derived from cancer cells.165 Therefore, new assays are being developed to detect specific cancer-associated glycoforms of mucins.165