Although a direct relationship between COMP and pro-inflammatory cytokine expression has been suggested in past strenuous exercise studies15,36 and cartilage disease studies,8 experimental evidence has not supported the existence of this relationship in joint specific cells.37,38 Alternatively, other known DAMPs associated with cartilage damage such as fibronectin fragments (FnFs) have been shown to trigger pro-inflammatory responses in joint cells. Here, COMP is linked to cartilage disease.