Levels of S100A11 in the synovial fluid (195.8 (20.2–974.2) vs. 26.8 (8.2–199.4) ng/ml; p < 0.0001) but not in the serum (14.1 (4.3–119.8) vs. 9.3 (5.0–30.2) ng/ml; p = 0.158) were significantly up-regulated in patients with RA compared to patients with OA when adjusted for age and sex (Fig. 3a, b). This evidence concerns the gene S100A11 and rheumatoid arthritis.