STAT3 and rheumatoid arthritis: Peripheral blood-derived CD4pos cells of RA patients were also characterized by a significantly higher STAT3 (59.7 ± 15.9 folds) and STAT5 expression (21.5 ± 4.4 folds) than healthy controls (7.0 ± 3.4 folds; p = 0.0002 and 1.3 ± 0.3 folds; p < 0.0001, respectively), which conversely remained unchanged during 12 months of CTLA4-Ig treatment (Fig. 2C).