['nt', 'an:', 'ial', '§', 'I', 'i', 'i', ' ', 'The', 'data', 'given', 'in', 'ail', 'tables', 'are', 'the', 'composite', 'of', 'at', 'least', '2', 'experiments.', 'Table', '1', 'Effect', 'of', 'feeder', 'cells', 'on', 'cytotoxicity', 'and', 'malignant', 'transformation', 'in', 'G23', 'cells', 'treated', 'with', 'MCA,', 'the', 'K-region', 'epoxide', 'of', 'MCA,', 'and', 'DMBA', 'Microsomal', 'Exzymes', 'and', 'Transformation', 'in', 'Vitro', ' ', 'Plating', 'efficiencies', '(%)', 'in', 'G23', 'cells', 'treated', 'with', 'No.', 'of', 'transformed', 'foci/no.', 'of', 'dishes', ' ', ' ', '.', 'Formation', 'K-region', 'K-region', 'Origin', 'of', 'of', 'water-', 'Control,', 'epoxide', 'Control,', 'epoxide', 'feeder', 'soluble', 'acetone,', 'MCA,', 'of', 'MCA,', 'DMBA,', 'acetone,', 'MCA,', 'af', 'MCA,', 'DMBA,', 'layer', 'used', 'products®', '0.5%', '10', 'pg/ml', '1.5', 'uefml', '10', 'ug/ml', '0.5%', '10', 'yg/ml', '1.5', 'pg/ml', '10', 'pe/ml', 'None', '36', '22.5', '(100)', '19.5', '(82)', '13.5', '(60)', '15.5', '(70)', '0/29', '12/14', '74i8', '18/19', 'Rat', '255', '38.5', '(100)', '16.6', '(42)', '25.0', '(65)', '11.5', 'GO)', '0/29', '48/16', '6/8', '14/18', 'Mouse', '243', '31.0', '(100)', '16.5', '(53)', '17.0', '($5)', 'nd.©', '0/6', '38/9', '910', 'ad.', 'Human.', '4', '24.5', '(100)', '20.0', '(82)', 'nd,', 'n.d.', 'O/12', '9/11', 'nd.', 'nad', ' ', '@', 'Water-soluble', 'products', '(in', 'zumoles)', 'formed', 'in', '24', 'hr', 'by', '10*', 'from', '260', 'pumoles', 'of', 'tritiated', 'MCA.', '>', 'Relative', 'plating', 'efficiencies', '(control', '=', '100%).', '“nd.,', 'not', 'deterniined.', 'Table', '2', 'Effect', 'of', 'inducers', '(BA,', 'PPO)', 'and', 'inhibitors', '(ANF)', 'of', 'microsomal', 'mixed-function', 'oxidases', 'on', 'toxicity', 'and', 'malignant', 'transformation', 'in', 'G23', 'cells', 'treated', 'with', 'MCA', 'and', 'the', 'K-region', 'epoxide', 'of', 'MCA', ' ', 'Plating', 'efficiency', '(%)', 'in', 'G23', 'cells', 'treated', 'with', 'No.', 'of', 'transformed', 'foci/no.', 'of', 'dishes', ' ', ' ', ' ', ' ', 'MCA', 'MCA', 'Formation', 'of', 'Control,', 'K-zegion', 'Control,', 'K-segion', 'water-soluble', 'acetone,', '15', '10.0', 'epoxide', 'acetone,', '1.5', '10.0', 'epoxide,', 'Pretreatment', 'products*', '0.5%', 'ug/ml', 'pg/ml', '1.5', 'pefmi', '0.5%', 'ng/ml', 'pg/ml', '1.5', 'ug/mt', 'None', '36', '23.5', '20.0', '20.0', 'ILS', '0/29', '2/18', '718', '44/25', 'BA', '(i', 'uM)', '61', '26.5', '21.5', '14.0', '15', '0/19', '8/7', '15/8', '248', 'BA', '(10', 'uM)', '24', '23.5', 'nd?', '20.0', 'nd.', '6/10', 'nd.', '4/10', 'n.d.', 'PPO', '(10', 'uM)', '60', '23.5', '18.0', '15.0', '11.0', 'O/t7', '20/16', '37/19', '4/18', 'ANF', '(1.5', 'pe/ml)', '5', '20.0', '22.0', '23.0', '3.0', 'o/10', 'o/9', 'of10', '25/15', ' ', '*', 'Water-soluble', 'products', '(in', 'yumoles)', 'formed', 'in', '24', 'hr', 'by', '10°', 'cells', 'from', 'n.d,', 'not', 'determined.', 'Table', '260', 'upmoles', 'tritiated', 'MCA.', '3', 'Effect', 'of', 'an', 'inducer', 'of', 'microsomal', 'hydrocarbon', 'metabolism', 'on', 'toxicity', 'and', 'malignant', 'transformation', 'in', 'G23', 'cells', 'treated', 'with', 'BA', 'and', 'DMBA', ' ', 'Plating', 'efficiencies', '(%)', 'in', 'G23', 'cells', 'treated', 'with', 'No.', 'of', 'transformed', 'foci/no.', 'of', 'dishes', ' ', ' ', 'BA', 'BA', 'Coniral,', 'DMBA,', 'Control,', 'DMBA,', 'Pretreatment', 'acetone,', '0.5%', '1', 'pefml', '§', 'pg/ml', '10', 'pefml', 'acetone,', '0.5%', '1', 'vg/mt', '5', 'pg/ml', '10', 'pefmi', 'None', '23.5', '19.0', '13.5', '18.0', '0/29', '0/10', '0/10', '88/22', 'BA', '(1', 'pM)', '24.0', '16.0', '10.0', '12.5', '0/29', '2410', '5/40', '65/22', ' ', 'carcinogens,', 'probably', 'epoxides', '(16,', '22).', 'These', 'findings', 'support', 'the', 'hypothesis', '(13,', '16,', '22)', 'that', 'enzymatic', 'activation', 'of', 'these', 'hydrocarbons', 'precedes', 'their', 'carcinogenic', 'activity', 'and', 'cast', 'some', 'doubts', 'on', 'the', 'suggestion', '(33)', 'that', 'these', 'enzymes', 'serve', 'merely', 'as', 'a', 'survival', 'mechanism', 'that', 'protects', 'the', 'organism', 'against', 'these', 'compounds.', 'Our', 'in', 'vitro', 'studies', 'suggest,', 'therefore,', 'that', 'the', 'generality', 'of', 'using', 'this', 'form', 'of', 'enzyme', 'induction', 'to', 'enhance', 'biochemical', 'defense', 'mechanisms', 'against', 'carcinogenic', 'hydrocarbons', 'as', 'environmental', 'hazards', '(33)', 'may', 'be', 'open', 'to', 'question,', 'The', 'opposite', 'effect,', 'an', 'increase', 'in', 'carcinogenic', 'activity', 'might', 'occur,', 'as', 'our', 'resulls', 'demonstrate.', 'Our', 'finding', 'that', 'higher', 'doses', 'of', 'an', 'inducer', '(BA)', 'APRIL', '1972', ' ', 'did', 'not', 'enhance', 'the', 'transforming', 'activity', 'of', 'BA', 'or', 'MCA', 'and', 'the', 'observation', 'by', 'others', '(19,', '23,', '25,', '34-37)', 'that', 'inducers', 'can', 'protect', 'against', 'hydrocarbon-induced', 'carcinogenesis', 'in', 'vivo', 'demonstrate', 'that', 'these', 'enzyme-dependent', 'activation', 'and', 'detoxication', 'mechanisms', 'are', 'very', 'finely-balanced’', 'processes', 'that', 'might', 'be', 'dangerous', 'to', 'manipulate.', '(In', 'this', 'connection,', 'the', 'influence', 'of', 'some', 'common', 'dietary', 'vegetables', 'on', 'the', 'activity', 'of', 'these', 'microsomal', 'enzymes', '(32,', '33}', 'may', 'be', 'alarming.)', 'Thus,', 'whether', 'a', 'hydrocarbon', 'will', 'transform', 'cells', 'or', 'not', 'may', 'depend', 'on', 'the', 'balance', 'between', 'the', 'activity', 'of', 'epoxide-forming', 'enzymes', 'and', 'of', 'epoxide-destroying', 'enzymes,', 'as', 'we', 'visualize', 'in', 'Scheme', '1.', '723', 'er', 'ae', 'eeaiaiaendaeradeeiecamilend', 'ames', 'ta', 'tind', 'seathiiadl', 'Acti', 'sccSaneanial', 'dain', 'aide', 'annie', ' ', '50258858']