GSK199 treatment does not alter joint and serum total citrulline levels significantly. (a) Synovial citrulline content from the knee. Arthritis was induced in mice by injections of bovine collagen in Complete Freund's adjuvant (CFA) at days 0 and 21. Mice were treated daily, beginning on day 0, with GSK199 (10, 30 or 30 mg/kg b.i.d.) in saline, saline alone, 0·25 mg/kg dexamethasone or were untreated. Mice which received no collagen type II (CII) immunizations (WT) were used as a baseline reference. (b) Serum citrulline content was also measured in the same mice at day 35. GSK199‐treated mice showed slightly decreased levels of total citrulline in the knee and serum, but only wild‐type (WT) mice and dexamethasone‐treated animals had statistically significant decreases in citrulline content compared to saline‐treated controls.