MBD4 and lymphoma: Early lymphomas were found in 20% of Mbd4−/−Mlh1+/+ and 4% of Mbd4 wild type, single and double heterozygous mice; lymphoid hyperplasia was found in 15% and 13% of Mbd4−/−Mlh1+/+ (Fig. 5e–5f) and the remaining cohort, respectively.