To test this hypothesis, IL-6 expression was measured in whole hip and knee synovia; IL-6 expression was 10.8-fold higher in RA hips than knees (two-tailed unpaired t-test with Welch's correction; P-value=0.042; n=13 RA hip, 22 RA knee, 13 OA hip, 15 OA knee; Fig. 3). This evidence concerns the gene IL6 and rheumatoid arthritis.