SF, which do not express the IL-6R, undergo pro-inflammatory sIL6R-mediated trans-signalling, facilitated by cell surface expression of GP130.33 We showed a strong correlation between YAP and GP130 expression in human RA synovium, in accordance with evidence that YAP upregulates GP130 expression in an autoregulatory loop,23 indicating that YAP plays a role in amplifying IL-6 signalling and maintaining invasiveness in RA-SF. Here, IL6R is linked to rheumatoid arthritis.