Here we test whether the targeting of chromosomal proteins HMG-14 and HMG-17 to transcriptionally active regions is due to coincidence of the synthesis of these proteins with the replication and assembly of active chromatin. Cells from the Burkitt's lymphoma line CA46 were synchronized with mimosine. The mRNA levels and the protein synthesis rates of HMG-14/-17 were determined at various stages during the S phase. The expression pattern of HMG-14/-17 was essentially constant throughout this phase of the cell cycle. The half-life for HMG-14/-17 protein corresponded to the doubling time of the cells. These results indicate that HMG-14/-17 are synthesized throughout S-phase and persist through the cell cycle. Targeting of HMGs to active genes is not simply due to the timing of their synthesis during S phase.