In our own investigations, using a panel of cultured malignant melanoma and pancreatic ductal adenocarcinoma cells, an apoptotic mode of cell death induced by D2O exposure was substantiated by annexin V-PI staining, pro-caspase 3 and PARP-1 cleavage, and pan-caspase inhibitor (zVAD-fmk) rescue, observed in both A375 melanoma and PANC-1 pancreatic ductal adenocarcinoma cells (Figure 1 and Figure 2). Here, PARP1 is linked to pancreatic ductal adenocarcinoma.