On the other hand, a recent report showed that the postnatal ablation of Sox9 dramatically decreases type II collagen mRNA and aggrecan contents; however, no histopathological signs of osteoarthritis were observed [52], indicating that the amount of extracellular matrix in articular cartilage is important but may not be necessary for the development of degradative changes in articular cartilage. Here, ACAN is linked to osteoarthritis.