Cycloheximide (1.0 ug/ml) reversibly induced a 1.7-fold increase in the distribution of cells in S phase and a 0.9-fold decrease in G1 phase in DNA histograms of human salivary adenocarcinoma cells (HSG). At this time, cycloheximide inhibited the synthesis of proteins by HSG cells and secretion of proteins in the media to 28.1% and 9% of the control values, respectively, which resulted in the almost complete arrest of cell reproduction. This indicates that HSG cells can pass through G1 to S phase even under the conditions of the arrest of protein synthesis.