CCN1 and rheumatoid arthritis: Both CCN1 and CCN2 are up regulated in synovial tissues, fibroblast-like synoviocytes and sera of RA patients (Chen et al. 2017a, b; Ding et al. 2016; Jie et al. 2015; Nozawa et al. 2009; Zhai et al. 2017; Sun et al. 2020; Zhu et al. 2015).