The transcription factors Oct-3/4 and BMI-1 are important for embryonic stem cell self-renewal (Niwa, 2001) and long-term proliferative capacity of normal haematopoetic and leukaemic stem cells (Valk-Lingbeek et al, 2004), and are expressed in cancer stem-like cells (Tai et al, 2005; Patrawala et al, 2006). Here, BMI1 is linked to cancer.