Fig. 7. ERK acts upstream PGE2. Effect of PGE2(100nM; 2hours) on the activity of the hepatic Na⁺/K⁺ ATPase in cells pre-treated for 30min with an ERK inhibitor (PD98059; 50 µM). Values are means ± SEM of at least 3 observations. Bars not sharing a common letter are considered significantly different from each other at p< 0.01.