CD4 and rheumatoid arthritis: Interestingly, the inhibitor of DRP1 (mdivi-1) could further promote the production of MtROS, whereas the inhibitor of OPA1 (MYLS22) had no significant impact on MtROS in RA CD4+PD-1+T cells (Fig. S6), which implies that decreased DRP1 is prominent in CD4+PD-1+T cells dysfunction.