PDPN and cancer: Podoplanin (PDPN), a 38-kDa type I transmembrane glycoprotein, is normally expressed in kidney podocytes, alveolar type I cells, osteocytes, basal keratinocytes, mesothelial cells and lymphatic endothelial cells,78 but its expression can be upregulated on the surface of different cancer cells and cancer-associated fibroblasts by tumour promoters including RAS, Src and the phorbol ester, 12-O-tetradecanoylphorbol-13 acetate (TPA).