Immunohistochemical staining specific for human cytokeratin 19 (CK19) on the PDX tissue confirmed a human origin of the epithelial cell compartment, with better staining in the moderately- to well-differentiated models compared to the poorly differentiated esophageal tumors EAC023 and EAC027 (Figure 1C,F). Here, KRT19 is linked to neoplasm of esophagus.