Fig. 3.

EP4, PKA, Rap, and ERK1/2 are involved in the PGE₂ activation of 90-kDa ribosomal S6 kinase (p90RSK). Cells were lysed, and p-p90RSK and the loading control protein β-actin were analyzed by Western blot analysis. A: effect of the EP4 antagonist ONO. p-p90RSK is expressed as the fold increase versus the control. Data are means ± SE from 6 separate experiments. *P ≤ 0.05 vs. PGE₂. B: effect of inhibition of ERK1/2 with the MEK inhibitor U-0126 (U; 10 μM). p-p90RSK is expressed as the fold increase versus the control. Data are means ± SE from 3 separate experiments. #P ≤ 0.01 vs. PGE₂. C: effect of Rap. p-p90RSK is expressed as the percentage of PGE₂ stimulation of NVMs transfected with control vector. Data are means ± SE from 5 separate experiments. #P ≤ 0.01 vs. the control vector. D: effect of PKA inhibition with H89. Data are means ± SE from 5 separate experiments. #P ≤ 0.01 vs. PGE₂.