The rate of fork movement during DNA replication in mammalian cells.

DNA fiber autoradiography was used to measure the rate of replication fork progression along replication units in human diploid cells. The rate in different replication units differs very significantly and lies within the range 0.1 to 1.2 micrograms/min. However, no significant changes were found in the rate of fork movement along single replication units operating during long intervals of S phase. Moreover, the fork progression rate is constant in many replication units of human cells.