The findings of this study, combined with a previous observation describing how invasiveness of FLSs is patient specific – as the difference in invasiveness between patients is greater than the difference between two joints from one patient [34] – suggest that a regulated EMT-like process might play a role in development of an arthritic synovium, rather than a random process of tumour-like alterations caused by the presence of p53 mutations in RA synovium [8,9,34]. Here, TP53 is linked to rheumatoid arthritis.