PARP1 and hepatocellular carcinoma: In order to establish the apoptotic effect of aspirin, we evaluated both the number of Annexin V-positive cells by flow cytometry analysis [34] and the expression of cleaved PARP-1 by Western blot analysis [35] in two human epithelial cell lines: one from normal colon epithelium (NCM460 cell line) and one from hepatocellular carcinoma (HepG2 cell line).