PDPN and malignant mesothelioma: The Podoplanin (PDPN) is a transmembrane sialo-glycoprotein and its overexpression has been detected in many types of tumors, including squamous cell carcinoma, malignant mesothelioma, esophagus, Kaposi’s sarcoma, testicular seminoma and brain tumors, and is associated with poor clinical outcomes.