POU5F1 and cancer: Recently, investigations into the broader applicability of OCT4 as a marker in (cancer) stem cell biology showed that only OCT4A (and not OCT4B and OCT4B1) is specific to stem cell (like) populations (Tai et al, 2005; Lengner et al, 2007; Atlasi et al, 2008; Cantz et al, 2008; Sotomayor et al, 2009; Wang and Dai, 2010).