Evidence also suggests that EMT can serve as a survival mechanism for cancer cells to escape immunosurveillance and resist therapy-induced death.38 Multiple studies have observed a strong correlation between the level of mesenchymal cell markers and therapeutic resistance.21,39–42 For example, Farmer et al.42 demonstrated that an upregulation of stromal gene expression predicted resistance to preoperative chemotherapy with 5-fluororacil, epirubicin, and cyclophosphamide in estrogen receptor (ER)-negative breast cancer. This evidence concerns the gene ESR1 and breast cancer.