The expression of E2F-1 and ATM in CNE2/DDP and HNE1/DDP cells after transfection was detected via qRT–PCR (Fig. 2A) and western blotting (Fig. 2B, C) to further explore this relationship, and as a consequence, the transfection of E2F-1 shRNAs reduced the expression of E2F-1 and ATM in DDP-resistant NPC cells (all P < 0.05). Here, ATM is linked to nasopharyngeal carcinoma.