The function of ETAA1 (ETAA1 activator of ATR kinase, ENSG00000143971) is as follows. Replication stress response protein that accumulates at DNA damage sites and promotes replication fork progression and integrity (PubMed:27601467, PubMed:27723717, PubMed:27723720). Recruited to stalled replication forks via interaction with the RPA complex and directly stimulates ATR kinase activity independently of TOPBP1 (PubMed:27723717, PubMed:27723720, PubMed:30139873). Probably only regulates a subset of ATR targets (PubMed:27723717, PubMed:27723720). {ECO:0000269|PubMed:27601467, ECO:0000269|PubMed:27723717, ECO:0000269|PubMed:27723720, ECO:0000269|PubMed:30139873}.