FLT4 and Kaposi's sarcoma: Consistent with the highly vascular tumor tissue containing immature blood vessels that is the KS clinical presentation [85,86], there was evidence for up-regulation of vascular growth factors like angiopoietin-2 (ANGPT2) and at least three vascular endothelial growth factor (VEGF) receptors such as neuropilin-2 (NRP2), fms-related tyrosine kinase (FLT4) and kinase insert domain receptor (KDR) and associated members of this angiogenesis signaling pathway.