Figure 3. Ethambutol (EMB) did not induce membrane translocation of various protein kinase C (PKC) isozymes but did induce gene expression of PKCδ in retinal pigment epithelium (RPE). RPE50 cells were treated with 8.0 mM EMB for 0, 0.5, 1 and 3 h. Western blots of cytosolic and membrane PKCα, βII, and δ (A), and real time RT/PCR (B) of PKCδ were performed. In (A), ERK and tubulin were included as internal controls for cytosolic and membrane proteins, respectively. The results are representative of four repeated experiments. In (B), relative amounts of PKCδ mRNA for each sample were calculated, taking the sample of time zero as 1.0. The asterisks (* and **) indicate statistical significance (p<0.05 and p<0.005, respectively, n=3) between the indicated groups.