Mouse myoblast cells were engineered to express GFP-PCNA (proliferating cell nuclear antigen) as a marker for replication factories, and also immunostained for the DNA methylase Dnmt1. DNA was localized using Hoechst staining. The image shows two different typical S-phase patterns displaying GFP-PCNA (left), Dnmt1 (center) and DNA (right). Dnmt1 co-localizes with PCNA at replication foci.
C2C12 cells stably expressing GFP-PCNA were fixed,stained for DNA ligase and DNA and optical sections acquired with a Leica TCS confocal microscope.
See: Fig 2 in H Leonhardt et al. 2000 Dynamics of DNA replication factories in living cells. J Cell Biol 149:271-279