Multiple in-vivo experimental studies have shown that the expression of pro-apoptotic proteins (such as Bax, Fas, caspase-3, and caspase-8) is significantly reduced, while the expression levels of the anti-apoptotic protein Bcl-2 are significantly increased in both adjuvant/collagen-induced arthritis animal models and synovial tissue of RA patients (6, 7). Here, CASP8 is linked to rheumatoid arthritis.