NRG1 and neoplasm: The decrease in nuclear DKK-1 found at early stages may facilitate tumor progression based on the results of the ChIP analysis: nuclear DKK-1 regulates genes with antiproliferative action (i.e., NRG1, NRG3, MAP2K3, PREX2, FAM5B) and involved in apoptosis (i.e., BCL2A1, DAPK1) (GSE31170), which may add to the action of extranuclear DKK-1 inhibiting β-catenin target genes such as c-MYC or CCND1/cyclin D1.