Expression of membrane-associated prostaglandin E synthase-1 (mPGES-1) and cyclooxygenase-2 (COX-2) protein in articular cartilage sections from osteoarthritis patients. Paraffin-embedded section of cartilage from osteoarthritis patients were subjected to immunostaining for mPGES-1 (a) and COX-2 (d). As adsorption controls for mPGES-1 (b) and COX-2 (e), primary antibodies that had been reacted with mPGES-1 and COX-2 peptide (10 μg/ml) were used, respectively. As a negative control for mPGES-1, rabbit anti-human mPGES-1 was replaced with normal rabbit IgG (c). Representative findings from three patients are shown here.