MEN1 and tumor of parathyroid gland: Thus, Men1+/− mice develop tumours consistent with MEN1 (Crabtree et al., 2001, Bertolino et al., 2003a, Bertolino et al., 2003b, Biondi et al., 2002, Loffler et al., 2007a, Loffler et al., 2007b, Harding et al., 2009), which is characterised by the occurrence of tumours of the parathyroid glands (in ∼95% of patients), pancreatic islets (in ∼40% of patients) and the anterior pituitary (in ∼30% of patients) (Thakker, 2013).