POU5F1 and colorectal carcinoma: To confirm the emergence of CSCs from cultures of CoPEC-infected cancer cells, we investigated the expression and sub-cellular location of NANOG, OCT-3/4, SOX2 (SRY-box transcription factor 2), KLF-4 (Kruppel-like factor 4), and c-MYC, which are key transcription factors in cell reprogramming and stem cell pluripotency52 and used to identify CSCs in a variety of cancers, including CRC.53 Immunofluorescence experiments revealed the expression and accumulation of these four transcription factors in the nuclei of cells at 3 weeks post-infection with 11G5 (Figure 4a left panel).