FUT9 (fucosyltransferase 9) is an α1,3-fucosyltransferase that catalyzes the addition of fucosyl moieties to N-acetylglucosamine within type 2 lactosamine structures on glycoproteins and glycolipids 1. This enzymatic activity generates Lewis x (Lex/CD15) and Lewis y (Ley) antigenic epitopes, which mediate cell adhesion and differentiation 2. FUT9 is expressed early during human embryogenesis, particularly in brain tissue where it likely supports neuronal stemness and neurite outgrowth in progenitor cells 2. The enzyme also generates VIM-2 antigen, a recognition epitope for selectin-mediated leukocyte adhesion 3. Clinically, FUT9 dysregulation is implicated in cancer progression. In esophageal squamous cell carcinoma, transcription factor ELF4 upregulates FUT9 to promote cancer stemness and metastatic properties 4. Similarly, FUT9 activation drives colon cancer cells toward stem cell-like phenotypes, increasing chemotherapy resistance and tumor growth 5. In non-small-cell lung cancer, microRNA-1246 suppresses FUT9 expression, reducing cancer cell proliferation and metastasis 6. Brain metastases from lung adenocarcinoma show FUT9-mediated fucosylation patterns associated with specific tumor subtypes and microenvironmental adaptations 3. These findings suggest FUT9 as a potential therapeutic target in multiple malignancies.