MTOR and fibrosarcoma: BCR-ABL1 drives the aberrant survival and proliferation of hematopoietic stem cells (HSCs) through the activation of multiple downstream pathways, including rat sarcoma (Ras)/Rapidly accelerated fibrosarcoma (Raf)/MEK/ERK, Wnt/β-catenin, Janus kinase (Jak)/Signal Transducer and Activator of Transcription (STAT), phosphatidylinositol 3-kinase (PI3K)/Akt/mechanistic target of rapamycin (mTOR), and SHH [92,93,94].