After deparaffin and rehydration, the paraffin-embedded heart sections (5 mm) were treated with 3% H 2 O 2 for 5 min. The nonspecific proteins were blocked with 5-10% goat serum for 10 min. For Beclin-1 staining, specimens were incubated with a rabbit antimouse Bcelin-1 Monoclonal antibody (1:200) at 4uC overnight, followed by incubation with a HRP conjugated goat anti-rabbit secondary antibody. The sections were finally incubated with DAB chromogenic substrate and counterstained with hematoxylin.