The gene encoding CCBE1 (Collagen and calcium-binding EGF domain-containing protein 1) is located on chromosome 18 in a region that is frequently found to be deleted in breast and prostate cancers. CCBE1 is a 406 amino acid secreted protein that contains two collagen-like domains and one calcium-binding epidermal growth factor (EGF-like) domain. In general, EGF-like domains include six cysteine residues that are usually involved in disulfide bonds. Calcium-binding EGF-like domains are subject to amino acid substitutions that disrupt their structure or calcium affinity, therefore altering protein function. Downregulation of the gene encoding CCBE1 is observed with high frequency in breast cancer, suggesting that loss of CCBE1 results in changes in cell adhesion and mobility due to its characterization as an extracellular protein. There are three named isoforms of CCBE1 which are produced as a result of alternative splicing events.