RET and neoplasm: The effect of SUN could be explained by targeting of different VEGF-unrelated receptor tyrosine kinases and other non-endothelial receptors such as CD117 and the receptors for Platelet Derived Growth Factor (PDGFR), and for Glial cell line-Derived Neurotrophic Factor (RET)43, as well as intracellular targets, showing a multifactorial effect on different signalling pathways regulating tumor cells44,45.