HBx survivin-dependently up-regulates HBXIP via DNA demethylation of HBXIP. (A) Schematic representation of the HBXIP promoter was shown. The activities of different fragments from HBXIP promoter were tested by luciferase reporter gene assays in HepG2-X, H7402-X and LO2-X-S cells (*P < 0.05, **P < 0.01, Student’s t test). (B, C) The methylation levels of HBXIP CpG sites were examined by bisulfite sequencing and MSP analysis in the cells and clinical tissues (n = 4), respectively. Eight CpG sites were analyzed. Closed and open circle present methylated and unmethylated CpG site, respectively. N represents adjacent nontumorous tissue; T represents HCC tissue. Bands in the ‘M’ and ‘U’ lanes are PCR products obtained with methylation-specific and unmethylation-specific primers, respectively.