MAP2K7 and fibrosarcoma: These lesions sustain RAS–RAF–MEK–ERK (mitogen-activated protein kinase, MAPK) signalling—that is, rat sarcoma small GTPases (RAS)—activating rapidly accelerated fibrosarcoma serine/threonine kinases (RAF), which phosphorylate MAPK/ERK kinases (MEK), culminating in the activation of extracellular signal-regulated kinases (ERK).