In his research activities, Nikolai Alekseevich Yudaev paid great attention to the study of the mechanisms of the biological action of hormones. He extremely liked the postulate that hormones regulate gene expression. Great interest in this problem predetermined the choice of the topic of this lecture at scientific readings devoted to his memory. The proposed publication is devoted to the consideration of new data on intracellular signal transduction of a number of hormones, such as growth hormone (GH), prolactin, and other protein hormones exhibiting a similar mechanism of biological action. It is well known that GR and prolactin are pituitary hormones, but not everyone knows that they can also be secreted by other tissues and are directly related to the regulation of immune processes.