Caspase-3 immunohistochemistry was performed as previously described method [4 (link),20 (link)]. The sections were incubated overnight with a rabbit anti–caspase-3 antibody (1:500; Santa Cruz Biotechnology, Dallas, TX, USA), and then incubated for another 1 hour with the biotinylated rabbit secondary antibody. The bound secondary antibody was then amplified using a Vector Elite ABC kit (Vector Laboratories). The antibody-biotinavidin-peroxidase complex was visualized using 0.02% DAB.