DKK1 and neoplasm: For example, the promoter methylation of genes such as those in the DKK family (e.g., DKK1, DKK3), the SFRP family (e.g., SFRP1, SFRP2),69, 70 and WIF1 (Wnt Inhibitory Factor 1) can lead to their downregulation or silencing, thereby lifting the inhibition on the Wnt pathway and causing its abnormal activation, which in turn promotes the proliferation and survival of tumor cells.71, 72