Figure 8. Human retinal microvascular endothelial cells were stimulated with neurotrophin-3 (NT-3), neurotrophin-4 (NT-4) or vascular endothelial growth factor (VEGF) to induce phosphorylation of extracellular signal regulated kinase (ERK).

Results were expressed relative to the phosphorylation level of ERK after stimulation with dilution medium (Control). (A) In the upper panel, data are shown from cells that were stimulated for 15 minutes with 10 to 100 ng/ml of NT-3 or NT-4 or 10 ng/ml of VEGF. (B) In the lower panel, we visualize the effects of a fixed concentration of NT-3 or NT-4 (100 ng/ml) added to the endothelial cells. The cells were lysed after 5, 15, 45 or 90 minutes and ERK phosphorylation as evaluated. Values are averages from 1 to 4 experiments ± SEM. * indicates significantly enhanced ERK phosphorylation (Mann-Whitney test).