ABCA2 and nasopharyngeal carcinoma: Thus, the DDP-resistant NPC cells in the following experiments were transfected with E2F-1 shRNAs to inhibit the expression of E2F-1, and such transfection could reduce the IC50 value of cells to DDP, with a decreased RI and downregulation of drug resistance-related genes (ABCA2 and ABCA5), which verified our assumption, and similar results were reported in previous studies.