Figure 2. Regulation of cyclooxygenase-2 (COX2) protein expression in retinal pigment epithelial (RPE) cells. The cells were stimulated for 6 and 24 h with high (+ 100 mM) NaCl, 200 mM sucrose, and the hypoxia mimetic CoCl₂ (150 µM), respectively. Protein levels were determined with western blotting of cell lysates. A: Examples of western blotting of two cell lines (above and below). The levels of the β-actin and COX2 proteins are shown. B: Mean ± standard error of the mean (SEM) cytosolic level of the COX2 protein. The data are normalized to the level of β-actin protein, and are expressed as a percent of the unstimulated control (100%). Each bar represents data obtained in four to five independent experiments with cell lines from different donors. Each experiment was performed with cell lines from four to five donors. Statistically significant difference versus unstimulated control: *p<0.05.