DKK1 and neoplasm: Dkk-1 is also upregulated by other malignant cell lines (Wirths et al, 2003; Forget et al, 2007), suggesting that serum Dkk-1 measurements may be useful for the evaluation of other types of malignancy, but the significance of Dkk-1 expression is not presently clear in tumours that do not affect bone.