In addition, FLS can promote various processes in RA by secreting different types of inflammatory cytokines, such as IL-6, IL-8, IL-1β, TNFα, and MCP-1, and matrix metalloproteinases (MMPs), such as MMP-1 and MMP-13, which has been shown to be closely related to the activation of cellular mitogen-activated protein kinase (MAPK) and nuclear factor-kappaB (NF-κB) signaling pathways [6–9]. Here, MMP1 is linked to rheumatoid arthritis.