MEN1 and neoplasm: Loss of menin expression in both endocrine and exocrine cells, as occurring in the Pdx1-Cre: MEN1 floxed/floxed mouse model, was not observed to alter DNMT1 expression in the exocrine pancreas, thereby suggesting that menin is important in maintaining the DNA methylome in endocrine cells, and this may provide an explanation for the predominant development of tumours in endocrine organs in patients with MEN1.