B2M and breast cancer: The second top canonical pathway (ignoring the first pathway related to HER-2 signaling in breast cancer) was “Virus Entry via Endocytic Pathways” confirming the relation of 3 (beta-2-microglobulin (B2M); Phosphatidylinositol 4;5-bisphosphate 3-kinase (PIK3CB) and protein kinase and Serine/threonine-protein kinase D1 (PRKD1)) out of the 13 peptide markers with the disease under study.