sentences:  The region (residues 296-359) consisting of 64 amino acids at the N-terminus of cell surface mesothelin has been identified as the functional binding domain (named IAB) for MUC16/CA125, suggesting the mechanism of mesothelin acting as a MUC16/CA125 functional partner in cancer development.Mesothelin is a tumor differentiation antigen that is normally present on the mesothelial cells lining the pleura, peritoneum and pericardium.Since mesothelin is overexpressed in several cancers and is immunogenic, the protein could be exploited as tumor marker or as the antigenic target of a therapeutic cancer vaccine.