Updated FTP location. Human breast cancer tissue samples from 18 patients with high-risk or low-risk MammaPrint breast cancer were analyzed. The membrane fractions were enriched, and the extracted proteins were reduced, alkylated, digested with Lys-C and Trypsin, and labelled with iTRAQ4plex: 114; high risk; 115; low risk. For this reanalysis, MS Datasets were processed for peak picking with MaxQuant v1.6.2.10, and the generated peak lists were searched against human entries of UniProt/Swiss-Prot release 2018_10 using three search engines: MaxQuant v1.6.2.10, X!Tandem v2015.04.01.1, and Comet 2015.02 rev. 0. The decoy database was generated by reversing sequences from the database. Then, the sum of the total number of matched b/y ions and the total number of amino acids comprising the peptide sequence tag were counted to score the reliability of peptide identification independent of these search engines. Finally, the 1% false discovery rate was controlled by the target-decoy approach with this score.