Effects of PPAR agonists on TNFα production in J774 macrophages. Cells were treated with increasing concentrations of fenofibrate (a), muraglitazar (b) or GW1929 (c) and stimulated with lipopolysaccharide (LPS). After 24 h incubation, TNFα accumulated into the culture medium was measured by ELISA. Results represent the mean + SEM (n = 4). *P <0.05 and **P <0.01 as compared to cells treated with LPS alone.