DKK1 and neoplasm: Dickkopf-1 (DKK1) is a 266–amino acid (35-kDa) secreted glycoprotein that is expressed in a variety of human tumors, including the pancreas, stomach, liver, bile duct, breast, cervix, esophageal, and prostate (75–77) and plays a functional role in human HCC cell migration, invasion, and tumor growth (78).