Figure 4. Receptor-mediated signaling 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. The following agents were tested: the inhibitor of the fibroblast growth factor (FGF) receptor kinase, PD173074 (500
nM), the blocker of vascular endothelial growth factor (VEGF) receptor-2, SU1498 (10 µM), the blocker of the endothelial growth
factor (EGF) receptor tyrosine kinase, AG1478 (600 nM), the inhibitor of the platelet-derived growth factor (PDGF) receptor
tyrosine kinase, AG1296 (10 µM), the inhibitor of transforming growth factor-β1 (TGF-β1) superfamily activin receptor-like
kinase receptors, SB431542 (10 µM), the broad-spectrum matrix metalloproteinase inhibitor 1,10-phenanthroline (1,10-Phen;
10 µM), and a recombinant human interleukin-1 receptor antagonist (IL-1RA; 1 µg/ml). Vehicle control was made with dimethyl
sulfoxide (DMSO; 1:1000). Each bar represents data obtained in three to 24 independent experiments with cell lines from different
donors. Each experiment was performed with cell lines from three to seven donors; in total, cell lines from 23 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.