Updated project metadata. we executed a study of serum proteome differences between trastuzumab-resistance and trastuzumab-response HER2-positive breast cancer patients using an isobaric TMT label-based multiplexed quantitative proteomic method in combination with a comprehensive functional bioinformatics analysis. An LC-MS/MS-based multiple/selective reaction monitoring (MRM/SRM) quantification method was applied to validate several candidate biomarkers.