Several factors including specific pathways such as stat3 signalling, the source of MSC, nature of MSCs (modified or naïve), choice of mouse models (syngeneic, allogeneic, and xenogeneic), types of breast cancer cell lines, and MSC secreted molecules such as exosomes appear to be responsible for the inhibitory effects on cancer [7, 91–94]. The gene discussed is STAT3; the disease is breast cancer.