STAT1 and rheumatoid arthritis: (ii) Consistent up-regulation of IFN and IL-10 pathway genes in the RA synovium: Besides STAT1, the other transcription factors like STAT2, IRF1, IRF9 and IRF8 which are part of IFN-mediated iNOS expression are up-regulated in at least one or more RA synovial datasets (Fig 2).