Proteoglycans are a family of glycoconjugates consisting of central core proteins with covalently attached glycosaminoglycan (GAG) side chains. Several proteoglycans participate in the development and maintenance of cartilage. Versican/PG-M positively regulates the formation of the mesenchymal matrix during the mesenchymal cell condensation, an essential process of chondrogenesis. Aggrecan, major proteoglycan in cartilage, forms the proteoglycan aggregate with hyaluronan and link protein. The aggregates provide cartilage with a gel-like property and resistant capacity to mechanical load through water absorption. Degradation of aggrecan by aggrecanases and matrix metalloproteinases leads to the cartilage degeneration.