BRAF belongs to the “rapidly accelerated fibrosarcoma” (RAF) family of mammalian cytosolic serine/threonine kinases, comprising ARAF, BRAF, and CRAF, which function in the mitogen-activated protein kinase (MAPK) signalling pathway downstream of RAS (reviewed in [20]) (Figure 2a). The gene discussed is RAF1; the disease is fibrosarcoma.