The Role of Adenosine 3',5'-cyclic Monophosphate in the Regulation of Mammalian Cell Division

A number of investigations have implied in recent years that a relationship exists between adenosine 3', 5'-cyclic monophosphate (cyclic AMP) and the growth of cells . Numerous experimental systems have been used to examine several different cell types. The result has been some definitive information about how cells divide, what role cyclic AMP plays in cell replication, and which periods of the cell cycle are affected by cyclic AMP . This review article will primarily consider the role of cyclic AMP in mammalian cells in culture in both resting and dividing states . The examination of cultured cells has the advantage that the intracellular levels of cyclic AMP and the enzyme activities which may be influenced either directly or indirectly by this cyclic nucleotide can be examined as a function of a reasonably welldefined chemical medium. Furthermore, the role that cyclic AMP exerts in cells that have been shifted from the resting to the dividing state may be assessed. Because of the many different approaches that have been used, some of the information obtained appears to be contradictory (although it still suggests a role for cyclic AMP in cellular proliferation) . The purpose of this report is to discuss individually the results that support specific aspects of the action of cyclic AMP at the morphological and molecular levels .