The cytoplasmic portion of the NS2 protein of hepatitis C virus (HCV) fused with a thioredoxin (TrX)-His tag was expressed in BL21 (DE3) cells and purified using an Ni-NTA His resin. Using a pull-down assay, a specific protein from the cell lysate of HepG2 cell lines was isolated together with immobilized truncated NS2 protein using Ni-NTA resin. Through peptide mass fingerprinting, this specific protein was found to be homologous to a repressor of transcription, ZNF136.