DKK1 and cancer: Besides its intrinsic effects on tumor cell proliferation and apoptosis, the WntT/β-catenin signaling pathway has been found to act on the tumor microenvironment and lead to immune evasion by reducing tumor infiltration of dendritic cells (DCs), NK cells, and T cells via multiple mechanisms, such as inhibition of CCL4 expression on cytotoxic T lymphocytes, CXCL10 expression on DCs, or increased expression of dickkopf WNT signaling pathway inhibitor 1 (DKK1), which prevents NK cell-dependent cancer cell lysis by reducing the expression of NK cell-activating ligands (22–24).