POU5F1 and cancer: SNAIL and SLUG have recently been proposed to selectively modulate self-renewal, pluripotency and proliferative activity of embryonic and of several epithelial and mesenchymal tissue and cancer stem cells without affecting the expression of stem cell transcription factors NANOG, SRY-box transcription factor 2 (SOX2) and POU class 5 homeobox 1 (POU5F1/OCT4).