DKK1 and endometrial cancer: Activation of the Wnt signaling pathway via alteration of the APC, Axin, CTNBB1, Wnt ligands, Wnt inhibitors Dickkopf3 (DKK3) and Dickkopf1 (DKK1), or the secreted Frizzled-related proteins may be a key driving event in the development of endometrial cancer.