Four different liquid chromatography-high resolution mass spectrometry (LC-HRMS) analyses were carried out for each ionization mode, in order to determine the molecular differences between the major subtypes of breast cancer (luminal A (LA), luminal B (LB), triple negative (TN) and human growth factor receptor 2 positive (HER2) and the healthy control (HC) groups. The gene discussed is ERBB2; the disease is breast carcinoma.