RAF1 and renal cell carcinoma: The rationale for targeting the Raf-MEK-ERK signaling pathway is classically exemplified by the activity of Sorafenib (Nexavar, BAY-43-9006) which was approved in 2005 for use in renal cell carcinoma treatment and inhibits VEGFR, PDGFR, c-KIT, C-Raf and B-Raf.