PARP1 and prostate cancer: Pretreatment of three different human prostate cancer cell lines (DU 145, PC-3, and LNCaP) with subtoxic doses of cisplatin or LA-12 enhanced TRAIL-induced cytotoxicity, as demonstrated by a significant increase in percentage of dead cells (annexin V/propidium iodide assay) and enhanced cleavage of caspase-3 and PARP (Fig 1A–1C) compared to the individual treatments.