DKK1 and ovarian neoplasm: When BRCA2mt ovarian tumors were compared with BRCA1mt tumors, eight genes (NOTUM, SFRP5, RNF43, ZNRF3, DKK1, DKK4, NKD1, and AXIN2) that negatively regulate Wnt signaling were upregulated in BRCA2mt tumors (Fig. 2A).