IGKC and breast benign neoplasm: Significantly up‐regulated in benign breast tumors were the proteins cystatin‐M (CST6), fucosidase alpha L2 (FUCA2), transferrin receptor protein 1 (TFRC), immunoglobulin kappa constant (IGKC), leucine‐rich alpha‐2‐glycoprotein (LRG1), IgGFc‐binding protein (FCGBP), and antithrombin‐III (SERPINC1), whereas the proteins histone H2A type 1‐B/E (H2AC4) and phosphoglycerate mutase 2 (PGAM2) were significantly down‐regulated compared to the control group (Figure 1e).