Podoplanin is a 40-43 kD type-I transmembrane sialomucin-type glycoprotein, also known as T1a, gp36, gp38, gp40, or Aggrus. Originally detected on the surface of podocytes, futher characterization showed podoplanin has a broad tissue distribution including many mesothelial cells, epithelial cells, follicular dendritic cells and a variety of tumor cells. It has been reported that podoplanin is the ligand of CLEC-2 and is involved in lymphatic vessel formation, platelet aggregation, and tumor metastasis. Podoplanin may serve as a useful marker for tumor diagnosis and prognosis.