Updated publication reference for PubMed record(s): 34605140. The Epstein-Barr virus nuclear antigen 2 (EBNA2) initiates and maintains the proliferation of infected B cells. In search of additional cellular strategies, that control EBNA2 function, we have performed a label-free mass spectrometry-based quantification of cellular proteins in EBNA2 immuno-precipitates and found polo-like kinase 1 (PLK1) to be bound to EBNA2. EBNA2/PLK1 complex formation is strongly enforced by EBNA2 S379 phosphorylation catalyzed by the mitotic CYCLIN B/CDK1 complex.