Abstract Background: Transforming growth factor-ß (TGF-ß) is a major inducer of epithelial-mesenchymal transition (EMT) in different cell types. TGF-ß-mediated EMT is thought to contribute to tumor cell spread and metastasis. Sialyl Lewis antigens synthesized by fucosyltransferase (FUT) 3 and FUT6 are highly expressed in patients with metastatic colorectal cancer (CRC) and are utilized as tumor markers for cancer detection and evaluation of treatment efficacy. However, the role of FUT3 and FUT6 in augmenting the malignant potential of CRC induced by TGF-ß is unclear. Methods: CRC cell lines were transfected with siRNAs for FUT3/6 and were examined by cell proliferation, invasion, and migration assays. The expression and phosphorylation status of TGF-ß downstream molecules were analyzed by western blot. Fucosylation of TGF-ß receptor was examined by lectin blot analysis. Results: Inhibition of FUT3/6 expression by siRNAs suppressed the fucosylation of type I TGF-ß receptor and phosphorylation of the downstream molecules, thereby inhibiting the invasion and migration of CRC cells by EMT. Citation Format: Rishu Takimoto, Masahiro Hirakawa, Fumito Tamura, Makoto Yoshida, Michihiro Ono, Yasushi Sato, Takahiro Osuga, Junji Kato. Fucosylated TGF-ß receptors transduce a signal for epithelial-mesenchymal transition in colorectal cancer cells. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1123. doi:10.1158/1538-7445.AM2014-1123