POU5F1B and colorectal carcinoma: This preferential subcellular localization was confirmed by immunohistochemistry analysis of endogenous POU5F1B in primary CRC biopsy samples, where a positive signal strictly correlating with the detection of POU5F1B transcripts by RT-PCR was detected in 4 out of 5 examined tumors but none of their matching normal tissue counterparts (Fig. 4b and Supplementary Fig. 4e, g).