Our immunofluorescence study revealed the presence of increased colocalization of MUC5AC and STn in the metastatic tissues injected with control cells compared to tumor tissues with ST6GalNAc‐I KO cells (Fig. 6H), suggesting that MUC5AC and its sialylation may play an important role in the development of liver metastasis. This evidence concerns the gene MUC5AC and neoplasm.