Figure 5. Transcription factor activity involved in mediating NaCl-induced expression of cyclooxygenase-2 (COX2) in retinal pigment epithelial (RPE) cells. The mRNA level was determined with real-time reverse transcription (RT)–PCR in cells cultured 6 h in iso- (control) and hyperosmotic (+ 100 mM NaCl) media, and is expressed as folds of the unstimulated control. A: The following compounds were tested: a hypoxia-inducible transcription factor (HIF)-1 inhibitor (HIF-Inh; 5 µM), the signal transducer and activator of transcription 3 (STAT3) inhibitor Stattic (1 µM), the nuclear factor (NF)-κB inhibitor CAPE (5 µM), the activator protein-1 (AP-1) inhibitor SR11302 (5 µM), and the cAMP response element-binding protein (CREB) inhibitor 666–15 (250 nM). B: Knocking down nuclear factor of activated T cell 5 (NFAT5) with small interfering RNA (siRNA) reduced the level of COX2 mRNA under hyperosmotic conditions. Nontargeted siRNA (siNon) had no effects. Each bar represents data obtained in three to nine independent experiments with cell lines from different donors. Each experiment was performed with cell lines from three to six donors; in total, cell lines from 21 different donors were used for all experiments shown. Statistically significant difference versus unstimulated control: *p<0.05. Statistically significant difference versus NaCl control: ●p<0.05. Statistically significant difference versus nontargeted siRNA: ○p<0.05.