FCGBP (Fc gamma binding protein) is a mucin-like glycoprotein secreted by intestinal goblet cells that serves as a critical component of mucosal innate defense 1. Structurally, FCGBP forms disulfide-linked heterodimers with trefoil factor family member TFF3 and mucin-2, creating high-molecular-weight complexes that inhibit bacterial attachment to mucosal surfaces, reduce pathogen motility, and facilitate clearance 23. These TFF3-FCGBP complexes have been identified in the intestine, respiratory tract, saliva, and endocervix, where they support mucosal innate immunity 45. Beyond mucosal defense, FCGBP plays pathological roles in cancer: elevated expression correlates with advanced ovarian cancer stage and poor prognosis, with mechanistic studies showing FCGBP promotes tumor progression via NF-κB-mediated IL-6 expression and JAK-STAT pathway activation 6. In primary liver cancer, FCGBP+ tumor-associated macrophages within necroptotic microenvironments drive differentiation toward intrahepatic cholangiocarcinoma rather than hepatocellular carcinoma 7. Altered FCGBP expression is implicated in inflammatory bowel diseases including Crohn's disease and ulcerative colitis 2, and germline FCGBP variants are associated with hereditary diffuse gastric cancer susceptibility 8. Thus, FCGBP functions as both a protective mucosal component and an oncogenic regulator warranting investigation as a diagnostic and therapeutic target.