We discovered that (a) SLC35C1 is present not only in Golgi apparatus and ER but also in early and late endosome; (b) SLC35C1 is reduced in colon cancer tissue, where β‐catenin is found increased; (c) silencing SLC35C1 in cells induces cell proliferation and enhances the colony formation ability; and (d) silencing SLC35C1 in cells induces Wnt3a secretion and activates canonical Wnt pathway. Here, WNT3A is linked to colonic neoplasm.