The SPEM cell lineage-specific marker AQP5 was continuously and strongly expressed at the apical side of single-layered cells in metaplastic gastroids cultured alone, but was only intermittently and faintly expressed in cells within polypoid projections in gastroids co-cultured with metaplasia- or cancer-derived fibroblasts (Supplementary Figure 11B and D). This evidence concerns the gene AQP5 and cancer.