Effect of dibutyryl cyclic AMP on leucine incorporation in L5178Y cells II. Effect of actinomycin and heat shock

3H‐leucine incorporation was assayed in L5178Y cells as a measure for protein synthesis. Protein synthesis was inhibited by short duration heat shock, actinomycin, cordycepin or a combination of these agents. Dibutyryl cyclic AMP had little or no effect upon protein synthesis in control cells. Dibutyryl cyclic AMP, however, stimulated protein synthesis in cells previously heat shocked and/or inhibited by actinomycin or cordycepin. The results have been interpreted to indicate that the cyclic nucleotide stimulated protein synthesis by influencing the metabolism of some species of RNA which may regulate translation.