RAF1 and cancer: Rat sarcoma virus (RAS)-rapidly accelerated fibrosarcoma (RAF)-mitogen-activated protein kinase (MAPK)-extracellular signal-regulated kinase (ERK) signaling is a well-established pathway that controls cell growth, proliferation, and survival in normal cells and cancer cells.331,332 Core components of RAS-RAF-MAPK-ERK signaling include the small GTPase RAS, the serine/threonine kinase RAF, the protein kinases MEK1/2 and ERK1/2.