Figure 5. Caspase 8 enzymatic activity in rat retinas. A: The level of protein expression of caspase 8 in the rat retina was evaluated by western blotting. Diabetes increased the cleaved form of caspase 8 (activated form), whereas treatment with etanercept reduced the diabetes-induced cleavage of caspase 8. B: The enzymatic activity of caspase 8 in the rat retina was evaluated by a colorimetric analysis. Diabetes increased the activity of caspase 8 as measured by the conversion of its specific substrate. Treatment with etanercept reduced the diabetes-induced caspase 8 activation and therefore the conversion of its substrate and correlates with the reduction in the cleaved form of the caspase as measured by the western blot shown.