RET and neoplasm: Sorafenib has been found to inhibit several receptor tyrosine kinases (RTKs) that are involved in neo-angiogenesis and tumor progression, such as vascular endothelial growth factor receptors (VEGFR1-3), platelet-derived growth factor receptors (PDGFR a and b), tyrosine protein kinase Kit (c-kit), fms-related tyrosine kinase 3 (Flt3), Colony stimulating factor 1 receptor (CSF-1R) and Rearranged during Transfection (RET) [2].