As noted above, MKI67+ ductal cells (cluster 5) may function as a type of regenerative/proliferative tumor cell since they were exclusively found in tumor but not normal tissues, while CEACAM5+ ductal cells (cluster 3) may represent a class of malignant metastatic cells with high level of CNV that dominate the HM tissues (Fig. 2a). Here, MKI67 is linked to neoplasm.