DKK1 and neoplasm: On the other hand, MSCs exhibit anti-tumor capacity by: 1) upregulating the expression of the negative regulators p21 and cyclin D2 to block tumor proliferation and induce apoptosis (78, 79); 2) enhancing the inflammatory response (80); and 3) inhibiting tumor proliferation by inducing Dickkopf-related protein 1 (DKK-1) expression via the AKT signaling pathway (81).