Hormone receptors and cyclic nucleotides; Significance for growth and function of tumors

The evidence for the suggested roles of cyclic nucleotides as regulators of cellular proliferation in normal, transformed and neoplastic cells is reviewed. It is concluded that cyclic nucleotides are not universal regulators of cellular proliferation $\text{in vivo}$ or $\text{in vitro}$. The evidence which points to the involvement of cyclic nucleotides in the regulation of other aspects of cellular metabolism in neoplastic cells is presented. Finally, the implications of the experimental evidence for the clinical aspects of cancer is discussed.