NPC/Bmi1siR blocked cell cycle progress in HepG2/RC cells. (A) Cell cycle profile of HepG2/RC cells treated with PBS, cisplatin (5 μM), NPC (5 μM cisplatin), and NPC/Bmi1siR (5 μM cisplatin and 50 nM Bmi1 siRNA) for 24 h. Cells were fixed by ethanol and labeled with propidium iodide, then analyzed for fluorescent DNA content with flow cytometry. (B) Western blotting of cyclin A2, cyclin B1, cyclin D1 and cyclin E1 in HepG2 cells treated with PBS, cisplatin (5 μM), NPC (5 μM cisplatin) or NPC/Bmi1siR (5 μM cisplatin and 50 nM Bmi1 siRNA) for 24 h. (C) Quantification of the western blotting bands. Data are expressed as mean ± SEM of 3 independent experiments. (D) Immunofluorescence of cyclin D1 in HepG2/RC cells treated with PBS, free cisplatin, NPC or NPC/Bmi1siR. Pictures were taken under a fluorescence microscope with a magnification × 100.