ABCB1 and rheumatoid arthritis: As a preclinical drug, RN486 could effectively treat rheumatoid arthritis (RA).[30,31] In addition, RN486 completely suppressed systemic lupus erythematosus (SLE) progression in a mouse model of spontaneous SLE.[32] Our previous study revealed a significant off-target reversal effect of RN486 on ABCB1-meditated MDR.[33] However, uncertainty persists on whether RN486 has the off-target reversal impact on ABCG2-mediated MDR.