Among them, IL-21, IL-17A, and IFN-γ triggered the abnormal JAK/STAT signaling in the synovium, leading to joint destruction [118], while TNF-α activated the NF-κB pathway, enhancing TNFR-II expression and stimulating RANKL secretion in RA-FLS, thereby facilitating osteoclastogenesis [103]. This evidence concerns the gene IL21 and rheumatoid arthritis.