ATM and nasopharyngeal carcinoma: Finally, the transfection of ATM lentiviral activation particles could significantly enhance the expression of ATM without any significant effects on the expression of E2F-1; however, the effect of ATM overexpression on DDP-resistant NPC cells was reversed by E2F-1 shRNA, indicating that E2F-1 may modulate the sensitivity of DDP-resistant NPC cells by regulating ATM.