Affiliation: | 1. Pregnancy Research Branch (D.R.M.), National Institute of Child Health National Cancer Institute, National Institutes of Health, Bethesda, Md. 20205, U.S.A.;2. Human Development and the Laboratory of Molecular Carcinogenesis (D.M.W. and R.H.M.), National Cancer Institute, National Institutes of Health, Bethesda, Md. 20205, U.S.A. |