CDX2 is typically expressed in intestinal epithelium and serves as a marker of intestinal differentiation, whereas CK7 and CK20 expression patterns assist in distinguishing between gastric and intestinal phenotypes and can provide insight into the adenocarcinoma lineage.2,8,9 Emerging data suggest that mixed tumors may share a common clonal origin, with later molecular divergence driving NE and non-NE phenotypes. The gene discussed is CDX2; the disease is adenocarcinoma.