DKK1 staining was observed in some cancer epithelial cells, identified by the co-expression with a pan-cytokeratin (PanCK) marker, and in PDGRFa+ and aSMA+ stromal populations in all tumor types (Fig. 2D–F), while it was not detected in the terminal duct lobular unit of normal breast tissue (Supp Fig. 2E). The gene discussed is DKK1; the disease is cancer.