Figure 6: Effect of GRK2 inhibition on apoptosis. (a) The corpus cavernosum was stained with terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick end-labeling (TUNEL, red) and 4,6-diamidino-2-phenylindole (DAPI, blue) for apoptotic cells and cell nuclei, respectively (magnification ×200, scale bars = 50 μm). (b) Bar graphs represent quantitative image analysis for TUNEL assay. (c) Caspase-3 and cleaved caspase-3 protein expression was measured by western blot analysis. β-actin was used as a loading control. (d) Expression levels of caspase-3 and cleaved caspase-3 protein were normalized to β-actin. (e) Caspase-3 activity was presented as the fold change relative to the non-diabetic controls. Results were reported as mean ± standard deviation (s.d.). *p < 0.05, the indicated group versus control group; *P< 0.05, the indicated group versus T2DM+vehicle group; n = 20 per group. All results are representative of three independent experiments. GRK2: G protein-coupled receptor kinase 2; T2DM: type 2 diabetes mellitus.