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Corey-Pauling-Koltun molecular model of 13-cis-retinoic acid. Carbon atoms are shown in black, hydrogen atoms in white, and oxygen atoms in red. See page 487. [Trudy Nicholson, National Institutes of Health, Bethesda, Maryland]


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Science. ISSN 0036-8075 (print), 1095-9203 (online)