STAT6 and rheumatoid arthritis: Several preclinical studies supported the contribution of the JAK-STAT pathway to RA, such one by Ulf Müller-Ladner and collaborators [52] from Germany and Switzerland who reported that the synovium from joints of patients with RA expressed IL-4 STAT (STAT6), a finding supported by several subsequent publications reporting the expression of JAK-STAT-SOCS pathway components in the synovia of patients with RA.