Aromatase-deficient (ArKO) mice have a phenotype of increased adiposity - Jones, M E; Thorburn, A W; Britt, K L; Hewitt, K N; Wreford, N G; Proietto, J; Oz, O K; Leury, B J; Robertson, K M; Yao, S; Simpson, E R (Proc Natl Acad Sci USA, 2000)