HCC cells were cross-linked with 1% formaldehyde for 10 min at room temperature before the ChIP assay. The EZ-Magna ChIPTM Chromatin Immunoprecipitation Kit was purchased from Millipore for the ChIP assay. According to the manufacturer's instructions, proteins were cross-linked with 1% formaldehyde after cell lysis and DNA shearing with 15 cycles of sonication. Next, immunoprecipitation was conducted using the GLI1 antibody (Cell Signaling Technology, Danvers, MA, USA), normal rabbit IgG (Santa Cruz) as a negative control (IgG group) and anti-RNA Polymerase II antibody as the positive control (Input group). Following immunoprecipitation, cross-links were removed and immunoprecipitated DNA was purified and then amplified by qRT-PCR using the SYBR Green PCR Master Mix (Applied Biosystems). The primers used to detect the CtBP2 promoter were designed as follows: Forward: 5′-GCCGAACTCAGGGTAGTGAG-3′; Reverse: 5′-CGT CCTGACGTCTCAAGGTT-3′.
