Villin is a cytoskeletal protein with a molecular weight of 95kDa, which is an actin binding protein. It exists in the cytoskeleton of microvilli and plays a crucial role in maintaining the brush like edge tissue structure. Normally distributed in the intestinal epithelium and renal proximal tubule epithelium, it can be used for the differential diagnosis of intestinal epithelial derived tumors and non-intestinal epithelial tumors, and can also serve as a reference indicator for the diagnosis of gastrointestinal neuroendocrine tumors.