DNA replication is one of the most important events in living cells, and it is 
still a key problem how the DNA replication machinery works in its details. A 
replication fork has to be a very dynamic apparatus since frequent DNA 
polymerase switches from the initiating DNA polymerase alpha to the processive 
elongating DNA polymerase delta occur at the leading strand (about 8 x 10(4) 
fold on both strands in one replication round) as well as at the lagging strand 
(about 2 x 10(7) fold on both strands in one replication round) in mammalian 
cells. Lagging strand replication involves a very complex set of interacting 
proteins that are able to frequently initiate, elongate and process Okazaki 
fragments of 180 bp. Moreover, key proteins of this important process appear to 
be controlled by S-phase check-point proteins. It became furthermore clear in 
the last few years that DNA replication cannot be considered uncoupled from DNA 
repair, another very important event for any living organism. The reconstitution 
of nucleotide excision repair and base excision repair in vitro with purified 
components clearly showed that the DNA synthesis machinery of both of these 
macromolecular events are similar and do share many components of the lagging 
strand DNA synthesis machinery. In this minireview we summarize our current 
knowledge of the components involved in the execution and regulation of DNA 
replication at the lagging strand of the replication fork.