The NPC cell lines 5-8F and CNE2 were transfected with either scrambled sequences (as negative control (NC)) or siRNAs that target PVT1 (siPVT1) and exposed to 6 Gy radiation; 48 h later, the cells were collected to detect the expression levels of the cleaved (activated) caspases and PARP49. The gene discussed is PVT1; the disease is nasopharyngeal carcinoma.