Moreover, in malignant epithelial cells, the expression of several tumour‐specific genes (CLDN4, CLDN7, TFF3; p < 2.22 × 10–16) was significantly upregulated compared with that in the non‐malignant epithelium, whereas non‐malignant epithelial cells strongly expressed several genes associated with gastric mucus and digestive enzyme secretion (MUC5AC, GKN1, PGC, LIPF; p < 7.4 × 10–9, Figure S3B). Here, CLDN4 is linked to neoplasm.