After routine deparaffinization and hydration, the tissue sections from mouse tumor tissue specimens of each group were boiled in a microwave oven for 10 min for antigen retrieval followed by washing three times with PBS (pH 7.4). Then, they were treated with 3% hydrogen peroxide for 25 min and washed three times with PBS (pH 7.4). Subsequently, the tissue sections were blocked in blocking buffer containing 3% BSA and incubated with anti-cleaved caspase-3 antibodies overnight at 4 °C followed by incubating with the secondary antibody and DAB. The sections were counterstained using hematoxylin for 3 min and washed under tap water. The images were captured by the Leica microscope.