MTOR and sarcoma: Future research not only in MPNST, but also other sarcomas is directed increasingly at exploring combinatorial therapeutic strategies that target multiple signaling pathways including the BCR-ABL1 TKIs imatinib, EGFR TKI erlotinib, mTOR inhibitor combined with Hsp90 inhibitor ganetespib, anti-VEGF monoclonal antibody bevacizumab, multikinase (CSF-1R) inhibitor pexidartinib, multikinase (RAF/MEK/ERK/VEGFR/PDGFR) inhibitor sorafenib and others [13,15,16,17,39,40,50,52,53,54,57,58].