PTK2 and rheumatoid arthritis: Activation of DKK-1 and the TNF-alpha-stimulated integrin-related FAK signaling could induce the dissociation of beta-catenin/E-cadherin, which in turn promoted RA fibroblast-like synoviocytes (FLS) migration [26], and such dysregulated DKK-1 pathway could be involved in the pathogenesis and perpetuation of the inflammatory response in early clinically apparent stages of RA [27].