Effect of inflammatory microcrystals on the protein expression of COX-2 in human monocytes. Monocytes were incubated for (A) 24 hours with either MSU or CPPD crystals at the indicated concentrations, or (B) with crystals (0.6 mg/mL) for the indicated times and centrifuged. The cell pellets were then processed for evaluation of COX-2 protein expression by immunoblotting as described in Materials and Methods. A representative immunoblot is shown.