CCN1 and CCN2 have similar roles in RA pathogenesis, as both favour fibroblast-like synoviocite proliferation and induce osteoclastogenesis as well as angiogenesis (Chen et al. 2017a, 2017b; Ding et al. 2016; Ganesan and Rasool 2017; Nozawa et al. 2009; Zhang et al. 2009). Here, CCN1 is linked to rheumatoid arthritis.