Purpose: The main aim of the present study was to find out if serum-free treatment was able to up-regulate cyclooxygenase-2 (COX-2) pathway in A549 cells which were treated with serum-free medium for different hours. Methods: Prostaglandin E 2 (PGE 2 , a prostaglandin mainly from COX-2 pathway) in the supernatant synthesized by A549 cells, were determined with PGE 2 enzyme immunoassay kits. The protein expression of COX-1, 2 and PGE synthase (PGES) were detected by Western Blotting. Results:

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... yield of PGE 2 increased when A549 cells were treated with serum-free medium for 12 h, and decreased thereafter. The results of western blotting showed that changes in PGE2 were related to the variation of the expression of COX-2 and PGES. Conclusion: All the results suggested that the COX-2 pathway in A549 cells was up-regulated by serum-free treatment, the mechanism of which was associated with the increase of the expression of COX-2 and PGES.