HOTAIR and rheumatoid arthritis: Although genetic evidence points to important roles of HOTAIR in regulating RA [19], and the key processes occurring in HOTAIR-regulated cartilage damage have already been established [19–21], understanding the details of the kinetic interplay between HOTAIR and key mediators involved in cartilage damage, especially the overall dynamic characteristic and precise regulation mechanisms of HOTAIR-mediated Wnt/β-catenin signaling pathway contributions to the degradation of ECM and the pathogenesis of cartilage damage are still mysterious.