Celecoxib decreased intracellular cyclic adenosine monophosphate (cAMP) production by prostaglandin E2 (PGE2) and phosphorylated ERK (p-ERK) expression. A, cAMP level was increased by PGE2 at 15 minutes, which was downregulated by celecoxib. B, Leiomyoma cells were treated with PGE2 for various periods (0, 15, 30, 60, and 120 minutes) to identify time-dependent expression of p-ERK. C, At 30 minutes, expression of p-ERK was decreased compared to PGE2 or P4 treatments. The data are expressed as arbitrary units. The bars represent the mean ± standard error of values from triplicate experiments. a* indicates significant change relative to control, and b* indicates significant change relative to PGE2-treated cells. *P < .05.