{"type": "root", "children": [{"type": "p", "children": [{"type": "t", "text": "\nREX1, also known as ZFP42, has long been established as an embryonic stem cell (ESC) marker. Although its molecular function is still being elucidated, early studies have shown that REX1 plays a role during the differentiation of ESCs—potentially involving STAT signaling pathways—and is expressed not only in ESCs but also in human mesenchymal stem cells derived from young tissues and in certain cancer cells. This expression pattern suggests that REX1 may contribute to stem cell maintenance as well as cell fate decisions in diverse biological contexts."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "1"}]}, {"type": "t", "text": ""}, {"type": "p", "children": [{"type": "t", "text": "\nFurther investigations in human embryonic stem cells have revealed that REX1 expression marks a subpopulation within an otherwise homogenous pool of pluripotent cells. Using a sensitive reporter system inserted under the control of REX1 regulatory elements, researchers demonstrated that REX1 is co-expressed with key pluripotency markers such as OCT4 and TRA-1-60, yet its expression is rapidly lost upon differentiation. Notably, the loss of REX1 is associated with stable, lineage-primed states and accompanied by distinct changes in DNA methylation at the REX1 locus, highlighting an epigenetically regulated barrier that distinguishes the human pluripotent compartment from its murine counterpart."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "2"}]}, {"type": "t", "text": ""}, {"type": "p", "children": [{"type": "t", "text": "\nIn a related line of research aimed at understanding proteins that interact with conserved transcriptional regulatory elements, a novel exonuclease domain–containing protein—Elongin A-binding protein 1 (EloA-BP1)—was identified through yeast two-hybrid screening using the NH₂-terminal regions of transcription elongation factors. Although this work did not directly implicate REX1 in transcription elongation, the identification of proteins such as EloA-BP1 that bind regions with similarities to motifs found in various transcription regulators provides a broader context for understanding how interactions among different regulatory proteins might impact transcriptional programs in stem cells."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "3"}]}]}]}]}, {"type": "rg", "children": [{"type": "r", "ref": 1, "children": [{"type": "t", "text": "Dilli Ram Bhandari, Kwang-Won Seo, Kyoung-Hwan Roh, et al. "}, {"type": "b", "children": [{"type": "t", "text": "REX-1 expression and p38 MAPK activation status can determine proliferation/differentiation fates in human mesenchymal stem cells."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "PLoS One (2010)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1371/journal.pone.0010493"}], "href": "https://doi.org/10.1371/journal.pone.0010493"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "20463961"}], "href": "https://pubmed.ncbi.nlm.nih.gov/20463961"}]}, {"type": "r", "ref": 2, "children": [{"type": "t", "text": "Sonam Bhatia, Carlos Pilquil, Ivana Roth-Albin, et al. "}, {"type": "b", "children": [{"type": "t", "text": "Demarcation of stable subpopulations within the pluripotent hESC compartment."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "PLoS One (2013)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1371/journal.pone.0057276"}], "href": "https://doi.org/10.1371/journal.pone.0057276"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "23437358"}], "href": "https://pubmed.ncbi.nlm.nih.gov/23437358"}]}, {"type": "r", "ref": 3, "children": [{"type": "t", "text": "Kenji Tamura, Keikichi Miyata, Kazunori Sugahara, et al. "}, {"type": "b", "children": [{"type": "t", "text": "Identification of EloA-BP1, a novel Elongin A binding protein with an exonuclease homology domain."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "Biochem Biophys Res Commun (2003)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1016/s0006-291x(03)01556-0"}], "href": "https://doi.org/10.1016/s0006-291x(03"}, {"type": "t", "text": "01556-0) PMID: "}, {"type": "a", "children": [{"type": "t", "text": "12943681"}], "href": "https://pubmed.ncbi.nlm.nih.gov/12943681"}]}]}]}