Products of arachidonic acid metabolism will be measured in normal and malignant tissues and in culture fluids after maintenance of these tissues in organ culture. The following enzymes involved in the biosynthesis and metabolism of the prostaglandins will also be measured in these tissues before and during maintenance in tissue culture; 1) 15-hydroxyprostaglandin dehydrogenase (Types I and II), 2) delta 13,14-reductase, 3) prostaglandin interconvertase (PGE yields (reversibly) PGF), and 4) prostaglandin synthetase. All of these prostaglandins and their metabolites as well as the enzymes will be measured with the use of specific antibodies directed toward the product, the substrate, or both. BIBLIOGRAPHIC REFERENCES: Sheng-Shung Pong and Lawrence Levine. Biosynthesis of Prostaglandins in Rabbit Renal Cortex. Res. Commun. Chem. Path. Pharmacol. 13, 115-123 (1976). Sheng-Shung Pong and Lawrence Levine. Prostaglandin Synthetase systems of Rabbit Tissues and their Inhibition by Nonsteroidal Anti-inflammatory Drugs. J. Pharmacol. Exp. Ther. 196, 226-230 (1976).