Figure 2.

Effect of different length of treatment with LPS on (A) COX I/II protein levels in cultured RAW265.7 cells and (B) PGE2 levels in cell culture media. After treatment with 1 µg/ml LPS for 0, 2, 4, 6, 8, and 10 h, RAW264.7 cells were incubated with serum-free medium for an additional 2 h, and the supernatants were collected for measurement of PGE₂ levels by using an enzymatic immunoassay kit. Western blot analysis of cell lysates was performed with antibodies COX I or II, coupled with a secondary antibody conjugated with horseradish peroxidase. LPS, lipopolysaccharide; COX I and COX II, cyclooxygenase I and II, respectively.