Podoplanin was identified as a 43 kDa glycoprotein found in the cell membranes of glomerular epithelial cells (podocyte) (PMID: 9327748). It is a lymphatic marker because the expression of podoplanin has been detected in lymphatic but not blood vascular endothelium, and is useful as the marker of tumor-associated Lymphangiogenesis. Podoplanin has a function in developing testis, most likely at the level of cell-cell interactions among pre-meiotic germ cells and immature Sertoli cells. It may be involved in cell migration and/or actin cytoskeleton organization. When expressed in keratinocytes, PDPN induces changes in cell morphology with transfected cells showing an elongated shape, numerous membrane protrusions, major reorganization of the actin cytoskeleton, increased motility and decreased cell adhesion. It is required for normal lung cell proliferation and alveolus formation at birth. PDPN induces platelet aggregation. It does not have any effect on folic acid or amino acid transport and does not function as a water channel or as a regulator of aquaporin-type water channels.