Activating mutations in the mitogen-activated protein kinase (MAPK) pathway, which incorporates the enzymes RAS (rat sarcoma, encoded by HRAS, NRAS and KRAS genes), RAF (rapidly accelerated fibrosarcoma, encoded by ARAF, BRAF and CRAF genes), MEK (MAPK/extracellular-signal-regulated kinase—ERK, encoded by MEK1 and MEK2 genes), result in constitutive signaling that leads to oncogenic cell proliferation and cells escape from apoptosis [1, 2]. The gene discussed is RAF1; the disease is fibrosarcoma.