Barbosa et al. compared the anti-inflammatory activity of usnic acid incorporated in PCL microspheres and free usnic acid, applying in vivo assays (the subcutaneous air pouch and carrageenan-induced paw edema in rats) and measuring the inflammatory cytokines and neutrophil granule myeloperoxidase (MPO) levels, the inflammatory mediators secreted after stimulation of polymorphonuclear leukocytes released into injured tissue. The gene discussed is MPO; the disease is edema.