Tumor sections were stained with mucicarmine stain (Dako) and immunohistochemistry using the Dako EnVision system with the following antibodies: CK7 (Dako, mouse monoclonal, RTU), CK20 (Dako, mouse monoclonal, RTU), carcinoembryonic antigen (CEA, Dako, mouse monoclonal, RTU), p63 (BioCARE, mouse monoclonal, 1 : 20), CK5/6 (Dako, mouse monoclonal, RTU), MUC1 (BioCARE, mouse monoclonal, 1 : 100), MUC2 (Dako, mouse monoclonal, RTU), MUC4 (Invitrogen, mouse monoclonal, 1 : 400), MUC5 (Leica, mouse monoclonal, 1 : 50), and HER2-neu (c-erbB2, Dako, rabbit polyclonal, 1 : 3000). The gene discussed is MUC4; the disease is neoplasm.