KRT19 and neoplasm: In the immunohistochemical analysis, the expression of the gastroenteropancreatic and hepatobiliary epithelial marker cytokeratin 19 (CK19), which is normally expressed in the lining of the gastroenteropancreatic and hepatobiliary tracts and positively localized in the cytoplasm of S2-013 cells, was low in the EMT cells of tumor xenografts obtained from the S2-013-organoid model (Fig. 3H), whereas the EMT biomarker vimentin was present in the cytoplasm of EMT cells (Fig. 3I).