RAF1 and colorectal carcinoma: Regorafenib, a multikinase inhibitor approved by the FDA as second-line therapy in CRC, interacts with tyrosine kinase receptors involved in angiogenesis (VEGFR 1-3, TIE-2), oncogenesis (c-KIT, RET), stromal signaling (PDGFR-β, FGFR1), and intracellular signaling (c-RAF/RAF-1, BRAF).