RET and neoplasm: Sorafenib's targets include the serine/threonine kinases c-Raf and B-Raf, the receptor tyrosine kinases RET, Flt-3, and c-Kit, and receptor tyrosine kinases important in tumor angiogenesis, including the vascular endothelial growth factor receptor family (VEGFR1, -2, and -3) and platelet-derived growth factor-beta [8].