The method of hybridization in a dot was used to study the dynamics of expression of pRL genes inducible in dividing cells of the regenerating rat liver and c-myc oncogene after whole-body X-irradiation. As overall incorporation of mRNA into a polyribosomal fraction was inhibited the level of mRNA in the most studied pRL genes and c-myc oncogene within the translated mRNA increased. The maximum induction of pRL gene expression occurred 6-12 h following X-irradiation depending on radiation dose. It is suggested that X-radiation induction of pRL gene expression is related to the increased transcription of the corresponding mRNA since their level does not change in conditions of cycloheximide blockade of the protein synthesis.