MEN1 and Familial prostate cancer: Although no mechanism was previously proposed, heterozygous Men1 mutant mice (Men1±) carrying an inactivated Men1 allele (Bertolino et al., 2003) and mixed with C57BL6/129-Sv mouse strains developed prostate cancer as compared with wild-type (Men1+/+) littermates in aged mice (18 to 26 months) (Seigne et al., 2010).