To explore the ISGylated sites of DPP3. DPP3-Flag and the ISGylation system containing UBA7, UBE2L6, and ISG15 were co-transfected in HEK293T cells. Cells were harvested after 48 hours and lysed, then co-immunoprecipitation with anti-Flag antibody magnetic beads. The sample was verified by western blot. Then the sample was electrophoresed in polyacrylamide gel and LC-MS/MS was performed using gel containing Co-IP sample to identify the ISGylation sites of DPP3.