Stem cell and epithelial cell markers on progenitor epithelial cells were detected by immunofluorescence assay (IFA). Epithelial colony cells were fixed in methanol: acetone (1:1) for 3 min at room temperature and then blocked with 3% bovine serum albumin (BSA) for 30 min. Cells were incubated at 4uC with following primary antibodies: rabbit anti-human Oct4 (Santa Cruz Biotechnology), mouse anti-human SSEA-1(Millipore), goat antimouse cc10 (Santa Cruz Biotechnology), mouse anti-human pan cytokeratin, mouse anti-human cytokeratin 18 (Sigma), rabbit anti-human occludin (Invitrogen), mouse anti-human CD90, rat anti-mouse CD44 and mouse anti-pig CD29 (BD Pharmingen). After overnight incubation at 4uC, cells were washed and incubated for 1 h at room temperature with the following respective FITC-labeled secondary antibodies: donkey anti-goat IgG, goat anti-rabbit IgG, and goat anti-mouse IgG (Sigma). Cell nuclei were then counterstained with 49,6-diamidino-2-phenylindole (DAPI).