KDR and neoplasm: However, sorafenib also inhibits several receptor tyrosine kinases that may be involved in tumor angiogenesis and progression, e.g., human and murine vascular endothelial growth factor receptor-2 (VEGFR-2), VEGFR-3, platelet-derived growth factor receptor-beta (PDGFR-β), Flt3, and c-KIT [2], [3], [4].