CASP3 and neoplasm: To gain an understanding of the mechanism underlying the combinatorial effects of the drugs in vivo, we analyzed bona fide markers of DNA damage (γH2AX), cell death by apoptosis (γH2AX and caspase 3/7 activity) and cell cycle perturbation (pSer10 H3 levels and mitotic counts) in tumor extracts from MNHOC#22 and MNHOC#266 PDX bearing mice treated for 5 days with vehicle, single agents or the combination at the same doses used for antitumor activities.