Since the basal level expression of TARIL is clearly detected in the MH7A cells, we hypothesize that the interaction between endogenous TRAIL and upregulated DR5 induces apoptosis through the extrinsic death pathway in DHA-treated RA-FLS cells, as confirmed by the processing of caspase-8 (Figure 1C,E and Figure 5E). Here, CASP8 is linked to rheumatoid arthritis.