MTOR and sarcoma: Downstream signaling cascades include the rat sarcoma/rat sarcoma-activated factor/mitogen activated protein kinase/extracellular regulated kinase kinase (Ras/Raf/MEK/ERK) and the phosphatidyl-inositide 3 kinase/protein kinase B/mammalian target of rapamycin (PI3K/AKT/mTOR) pathways [9].