Mutation of MBD4 (normal function being the repair of methyl-CpG deamination events) occurs in microsatellite unstable tumours (Bader et al, 1999) and absence of the gene in MBD4 null mice leads to increased genomic mutations and tumour burden in APCmin mice (Millar et al, 2002). Here, MBD4 is linked to neoplasm.