Figure 9. Effect of diabetes on VEGF protein levels. Total protein was extracted from one retina of each rat. VEGF protein levels were measured with enzyme-linked immunosorbent assay (ELISA) and normalized to total protein for diabetic (black bars) and age-matched control (gray bars) rats at 4 and 12 weeks (mean ± SEM). The asterisk (*) indicates significantly different from age-matched control rats, p<0.05).