CDKN2A and lymphoma: Myc operationally cooperates with Bmi-1 in the induction of mouse lymphomas and the simplest interpretation is that while Myc activates the CDKN2A locus inducing apoptosis or arrest, Bmi-1 in a polycomb complex mediates repression of the locus via targeted epigenetic histone modifications and so the balance is shifted in favour of survival and proliferation [25,37].