Mesothelin also known as MSLN is a protein that in humans is encoded by the MSLN gene Cloning studies showed that the mesothelin gene encodes a precursor protein that is processed to yield mesothelin which is attached to the cell membrane by a glycophosphatidylinositol linkage and a 31-kDa shed fragment named megakaryocyte-potentiating factor (MPF) Although it has been proposed that mesothelin may be involved in cell adhesion its biological function is not known A knockout mouse line that lacks mesothelin reproduces and develops normally