Steroid Influences on Respiration, Glycolysis, and Levels of in the present experiments multiple mammary cancers were induced in rats, and the levels of six soluble pyridine nucleotide-linked enzymes

in the present experiments multiple mammary cancers were induced in rats, and the levels of six soluble pyridine nucleotide-linked enzymes were determined in the tumors before and after (a) the withdrawal of steroids by oophorectomy, (b) the administration of sex steroids, (c) preg nancy, and (d) lactation. It was found that these modifications of the steroid status exerted great effects on the levels of lactic dehydrogenase,' glucose-6-phosphate dehydrogenase, and malic en zyme (TPN) in the cancers. Changes in the en docrine status exerted smaller effects on the levels in the tumors of 6-phosphogluconic dehydrogen ase, isocitric dehydrogenase and malic dehydro