Figure 2
From: Polo-like kinase 1 (Plk1): an Unexpected Player in DNA Replication

Functions of Plk1 in DNA replication. During undisturbed DNA replication, Plk1 phosphorylation of Hbo1 promotes Mcm complex loading thus pre-RC formation. When DNA replication is under stress, checkpoint activation causes stalled replication fork. Plk1 phosphorylation of Orc2 promotes the maintenance of pre-RC on dormant origins.