The genetic changes associated with immortalisation, namely loss of p16, p15, p21 and p53, are among the most common known cancer-related changes, and these genes are frequently downregulated by methylation in ALL (Garcia-Manero et al, 2002; Roman-Gomez et al, 2002; Agirre et al, 2003). Here, CDKN2A is linked to acute lymphoblastic leukemia.