CDKN2A and lymphoma: BMI1 downregulates the expression of tumour-suppressor genes, such as p16INK4a and p14ARF (Valk-Lingbeek et al, 2004), transgenic mice have a high predisposition to lymphomagenesis, subtypes of human lymphomas harbour BMI1 gene amplification and overexpression and it induces cell immortalisation (Valk-Lingbeek et al, 2004; Raaphorst, 2005).