Sequestration of Rpa by HU-induced replicative stress results in its unavailability for NER. MEF lines of each genotype were mock treated (left panels) or globally exposed to 2 mM HU (right panels) to induce the arrest of replication forks, followed by local UV-C treatment. Then, cells were stained for CPD (green), Rpa (yellow), EdU (red) and for nuclei (blue). Irrespective of the Rev3 status, Rpa is hardly recruited to local UV damage in the presence of replication forks, arrested by HU.