DKK2 and cancer: By using patient-derived xenograft (PDX) models of ovarian cancer, the authors revealed that the expression of various Wnt/β-catenin target genes, including Axin2, DKK2, Lef1, and Lgr5, and the expression of the Wnt ligand WNT5A are upregulated in platinum-resistant PDX-derived cancer cells, compared with platinum-sensitive cancer cells [45].