Catalytic component of the DNA polymerase epsilon complex (PubMed:10801849).Participates in chromosomal DNA replication (By similarity).Required during synthesis of the leading DNA strands at the replication fork, binds at/or near replication origins and moves along DNA with the replication fork (By similarity).Has 3'-5' proofreading exonuclease activity that corrects errors arising during DNA replication (By similarity).Involved in DNA synthesis during DNA repair (PubMed:20227374, PubMed:27573199).Along with DNA polymerase POLD1 and DNA polymerase POLK, has a role in excision repair (NER) synthesis following UV irradiation (PubMed:20227374).