Articular cartilage superficial zone protein (SZP) is homologous to megakaryocyte stimulating factor precursor and Is a multifunctional proteoglycan with potential growth-promoting, cytoprotective, and lubricating properties in cartilage metabolism - Flannery, C R; Hughes, C E; Schumacher, B L (Biochem Biophys Res Commun, 1999)