In BC cells Mammalian target of rapamycin (mTOR) signaling stimulates MDSCs accumulation by regulating G-CSF, and MDSCs were found to mutually increase Tumor-initiating cells frequency by activating Notch in tumor cells, which in turn promotes G-CSF secretion, forming a feed-forward loop leading to further MDSCs expansion (30). The gene discussed is MTOR; the disease is neoplasm.