This protein is an auxiliary protein of DNA polymerase delta and is involved in the control of eukaryotic DNA replication by increasing the polymerase's processibility during elongation of the leading strand. Homotrimer. Interacts with FEN1A (PubMed:11851910). Interacts with POLL (PubMed:15206945). Interacts with RAD/GEN1 (PubMed:22247560). Interacts with DJA7 and DJA8 (PubMed:15806324). Expressed in proliferating tissues. Expressed in roots and root apex. Expressed at low levels in young leaves. Not detected in mature leaves (PubMed:11851910, PubMed:15150342). Highly expressed in shoot apical meristem (SAM). Expressed in flag leaves and panicles (PubMed:15150342). Induced by the cell cycle inhibitors aphidicolin and hydroxyurea (PubMed:11851910). Induced by gamma irradiation (PubMed:25124817). Induced by heavy ion irradiation (PubMed:27462908). Induced by UV and hydrogen peroxide. Down-regulated during sucrose starvation (PubMed:15806324). Belongs to the PCNA family.