This gene encodes a preproprotein that is proteolytically processed to generate two protein products, megakaryocyte potentiating factor and mesothelin. Mesothelin is a glycosylphosphatidylinositol-anchored cell-surface protein that may function as a cell adhesion protein. Alternative splicing results in multiple transcript variants, at least one of which encodes an isoform that is proteolytically processed. Mesothelin is over expressed in several human tumors, including mesothelioma, ovarian cancer, pancreatic adenocarcinoma and cholangiocarcinoma. The interaction between mesothelin and MUC16 (also known as CA125) may facilitate the implantation and peritoneal spread of tumors by cell adhesion. Dr. Mitchell Ho and colleagues at the National Cancer Institute identified the region (residues 296-359) consisting of 64 amino acids at the N-terminus of cell surface mesothelin as the functional binding domain for MUC16.