The phenotypic similarity of organoid-derived xenografts to their corresponding primary tumor was also demonstrated by H&E staining (Fig. 1b and Supplementary Fig. 2) and immunofluorescence (IF) analysis, the latter of which demonstrated expression of the cholangiocyte ductal markers, KRT19 and SOX9, but not the liver cell markers AFP (alpha fetoprotein) and albumin (Fig. 1c) in both primary tumors and organoids. The gene discussed is KRT19; the disease is neoplasm.