DKK1 and rheumatoid arthritis: Recently, an increasing number of studies have demonstrated the potentially diagnostic and/or prognostic values of DKK-1 in varied cancers, such as lung cancer [32–34], gastrointestinal cancers [23], pancreatic cancer [35], and hepatocellular carcinoma [36–38], as well as rheumatic disorders, including RA [24] and AS [39, 40].