FLT4 and neoplasm: Over the past two decades, many key factors have been identified as important regulators for tumor lymphangiogenesis (Tables 2 and 3), but the major focus in anti-lymphangiogenic therapy has been targeting through VEGF-C and -D, and their membrane receptor VEGF-R3 and coreceptor (Nrp-2) [157, 206, 217].