KDR and renal cell carcinoma: There are a number of examples of multi-target kinase inhibitors currently on the market that inhibit multiple oncogenic pathways within tumors simultaneously, including sorafenib (inhibits MAPK, VEGFR, PDGFR, and mast/stem cell growth factor receptor (cKit) for the treatment of renal cell carcinoma (RCC) and hepatocellular carcinoma (HCC) [28,29], vandetanib (inhibits rearranged during transfection (RET) kinase, VEGFR, and EGFR) for treatment of thyroid tumors [30], and pozopanib (inhibits PDGFR, VEGFR, and cKit) for treatment of RCC and sarcoma [31,32].