Downregulation of Bmal1 in chondrocytes promoted the expression of MMP13 and ADAMTS5, while downregulation of Per2 inhibited the expression of MMP13 and ADAMTS5, demonstrating that arthritis and oxidative stress can promote the onset and development of osteoarthritis by affecting the expression of clock genes in chondrocytes [41]. This evidence concerns the gene PER2 and Arthritis.