RAF1 and sarcoma: BRAF is part of the Rapidly Accelerated Fibrosarcoma (RAF) family (cellular RAF (CRAF), BRAF, and ARAF) of serine/threonine protein kinases and appears as the second tier of the MAP kinase pathway (rat sarcoma (RAS)-RAF- MAPK/ERK kinase (MEK)- extracellular signal-regulated kinases (ERK) cascade), involved in responses to growth signals (16).