The previous investigation revealed that insulin-like growth factor 1 (IGF-1) could upregulate the synthesis of ChS-rich aggregating proteoglycans even at the relatively high concentration of inflammatory factors such as IL-1 and TNF-α, indicating that IGF-1 has the potential to ease arthritis (McQuillan et al., 1986; Tyler, 1989). This evidence concerns the gene TNF and Arthritis.