MUC1 and glycogen storage disease VI: The neoplastic cells were immunohistochemically positive for the S100 protein, epithelial membrane antigen (EMA), p53 (Figure 2C) and alpha-1-antichymotrypsin (AACT) whereas maspin, gross cystic disease fluid protein-15 (GCDFP), ER, PgR and HER2 were negative.