DKK4 and neoplasm: Despite strong support for TH and its receptors in tumor suppression via Wnt inhibitor DKK4 induction and tumor oncogene Sp1 repression, the tumor-promoting effects of TH such as in increasing invasiveness via furin up-regulation and its negative association with expression of the gene nm23, thought to be a suppressor of metastasis, have also been reported (Figure 1) [74,83–85].