Pro-oncogenic activity of PROX1 was shown in colon cancer, renal carcinoma, and malignant astrocytic gliomas, whereas in pancreatic cancer, Kaposi sarcoma and kaposiform hemangioendothelioma, oral cancer, esophageal cancer, sporadic breast cancer, and neuroblastoma it was identified as a candidate tumor suppressor gene [24, 26, 27, 30, 35-37, 45-49]. The gene discussed is PROX1; the disease is Kaposi's sarcoma.