The antibody is reactive with the peptide core of gastric mucin (MUC5AC, earlier also described as mucin M1). Mucin is an important tumor-associated marker for adenocarcinomas. The antibody shows specificity to gastric mucosa, but is also reactive with stomach and colon carcinomas. Most breast carcinomas are negative. The antigen is localized in the cytoplasm.
Positive control: Gastric mucosa of stomach.