Intrinsically disordered protein that potentiates the transcriptional activator activity of JUN (PubMed:24263171, PubMed:28289210). Protects cells from stress-induced apoptosis by inhibiting reactive oxygen species (ROS) production and via regulation of the MAPK signaling pathway (PubMed:21357425, PubMed:25374899, PubMed:30658679). {ECO:0000269|PubMed:21357425, ECO:0000269|PubMed:24263171, ECO:0000269|PubMed:25374899, ECO:0000269|PubMed:28289210, ECO:0000269|PubMed:30658679}. This is the function of ENSG00000101951 (PAGE4, PAGE family member 4).