MTOR and fibrosarcoma: Once KRAS is bound to GTP, it activates more than 80 downstream signaling pathways, such as the mitogen-activated protein kinase (MAPK)–MAPK kinase (MEK), phosphoinositide 3-kinase (PI3K)–AKT–mechanistic target of rapamycin (mTOR), and rapidly accelerated fibrosarcoma (RAF)–MEK–extracellular signal-regulated kinase (ERK) [10].