FLT4 and hemangioendothelioma: Interestingly, overexpression of prospero-related homeobox-1 (Prox-1) in mouse hemangioendothelioma cells induces an invasive phenotype in vivo, enhances the migration rate in vitro, and significantly upregulates the expression of podoplanin (D2–40) and vascular endothelial growth factor receptor-3 (VEGFR-3) [34].