Current Topics in Cellular Regulation, Volume 19 analyzes the advances in the general area of cellular regulation. This book discusses the evidence indicating that synthesis of the histidine enzymes is regulated and drugs affecting ribonucleotide reductase. The analogy principle in comparative biochemistry of allosteric regulation of metabolism, steady-state model of glucose metabolism in adipose tissue, and sensitivity of enzyme activity to changing ion concentrations are also elaborated. This publication likewise covers the cAMP-dependent protein kinases of nervous tissue and amino acid sequences of IGF I and II. This volume is a good reference for biologists and researchers conducting work on the basic mechanisms involved in the regulation of diverse cellular activities.