MSCs have been reported to inhibit tumor progression via various paracrine factors in hepatocellular carcinoma [32], breast cancer [33], ovarian cancer, and glioma [34], these factors include insulin-like growth factor-binding protein 3 [32], transforming growth factor-β [35] and DKK1 [32, 34, 36, 37]. The gene discussed is DKK1; the disease is breast cancer.