Figure 5.

Intracellular cAMP levels after stimulation of OSC1 and OSC2 cells and fibroblasts by iloprost, PGE₂ and forskolin. Intracellular cAMP levels were determined by radioimmunoassay. To examine the cAMP response, OSC1 (A) and OSC2 (B) cells were stimulated with agents known to induce cAMP levels. Human skin fibroblasts (C) were used as a positive control. Iloprost failed to induce cAMP increase in OSC1 and OSC2 cells, whereas it was able to raise cAMP levels in fibroblasts (C). PGE₂ stimulated cAMP production only in OSC1 cells (A), whereas forskolin led to an increase in cAMP levels in all tested cell types. Representative results from four independent experiments are shown and displayed as mean ± SEM; asterisk indicates a P-value < 0.05. OSC, oesophageal squamous cell; PG, prostaglandin.