Among them, the rapidly accelerated fibrosarcoma (RAF), the mitogen-activated protein kinase/extracellular signal-regulated kinase (MEK), and the extracellular signal-regulated kinase (ERK) form the RAF-MEK-ERK signaling axis, the central and most thoroughly studied MAPK pathway [8,9] (Figure 1). The gene discussed is RAF1; the disease is fibrosarcoma.