To determine the cellular target of GCRV-I VP5, VP5-GFP was overexpressed in CIK cells, followed by immunoprecipitation using an anti-GFP antibody. The immunoprecipitated proteins were detected using Western blot and Coomassie Brilliant Blue staining . Subsequently, the cut strips were analyzed using liquid chromatography-tandem mass spectrometry (LC-MS/MS).