PDPN and mesothelioma: PDPN expression has been reported in many cancers, including squamous cell carcinomas (head and neck, lung, uterine, oral, and esophageal carcinomas), malignant gliomas [46,47], mesotheliomas [48], bladder cancers [49], osteosarcoma [50], ovarian cancer [51], and testicular tumors [52].