The tumor was positive for pan‐cytokeratin (an epithelial marker), p16 and CA125 (a marker of ovarian cancer) with patchy/focal positive staining for vimentin (a mesenchymal marker) (Figure 3); and negative (null) for p53 (Figure S4) and estrogen receptor (ER) (not shown). The gene discussed is ESR1; the disease is ovarian carcinoma.