HBV up-regulated the expression of miR-181a by increasing its promoter activity. (A) Relative expression of miR-181a in HepG2 and HepG2.2.15. (B) Relative expression of miR-181a in Ad-HBV or Ad-GFP infected HepG2 cells. miRNA abundance was normalized to U6 RNA. (C) Dual luciferase reporter analysis was performed to analyze miR-181a promoter activity in HepG2.2.15 and HepG2 cells. (D) miR-181a promoter activity in HepG2 cells with Ad-GFP or Ad-HBV infection. *P < 0.05, **P<0.01.