FLT3 and nonpapillary renal cell carcinoma: Sorafenib is an oral multikinase inhibitor that targets growth signaling and angiogenesis in ccRCC by blocking VEGF-2-receptor (VEGFR-2), VEGF-3-receptor (VEGFR-3), PDGF-β-receptor (PDGFR-β), RAF- 1, c-Kit protein (c-Kit), and FMS-like tyrosine kinase 3 (Flt-3) (43).