Collagen synthesis by cells synchronously replicating DNA. 
Replication and the performance of a differentiated function have been considered antagonistic processes.  When cells in culture are partially tially synchronized with 5-fluoro-2'-deoxyuridine (FUdR), the synthesis of the specialized protein (collagen) is not reduced during chromosomal replication (S period).  Collagen synthesis varies with general protein synthesis through the S period.