Studies have found that the toxic protein BFT-1 secreted by enterotoxigenic Bacteroides fragilis can promote the lysosomal degradation of NUMB by binding to NOD1, which is highly expressed on breast cancer stem cells, thereby activating the NOTCH1-HEY1 pathway, promoting breast cancer cell stemness and chemotherapy resistance to docetaxel (158). Here, HEY1 is linked to breast cancer.