IHC was performed on formalin-fixed paraffin-embedded tissue sections using (1:400 dilution) anti-human cleaved caspase 3 (cCasp3) (Catalog no. 9661L, Cell Signaling). Unstained sections (4 μm thick) were deparaffinized and rehydrated using standard methods. Antigen retrieval and staining were performed as previously described [27 (link)]. Slides were incubated in secondary biotinylated goat anti-rabbit IgG (10 μL/mL; Vector, BA-1000) diluted in 10% blocking solution (Peroxidase, Biocare Medical, catalog no. PX968)/90% TBST. Detection of the antibody complexes was by the avidin–biotin immunoperoxidase method. Images of cCasp3-stained tumor tissue were collected using an Axiolab 5 microscope (ZEISS). Images (n=3/mouse) were collected for each treatment group (n=3 mice/group). Image J was used to remove background color and the total image was measured for mean grey value.