Affinage

TSPAN4

Tetraspanin-4 · UniProt O14817

Length
238 aa
Mass
26.1 kDa
Annotated
2026-06-10
74 papers in source corpus 10 papers cited in narrative 11 extracted findings
Cross-family judge vs UniProt: Affinage preferred faithfulness: 7/7 claims corpus-supported (100%)

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

TSPAN4 is a tetraspanin that organizes specialized plasma-membrane microdomains and drives the biogenesis of migration-associated membrane structures, including retraction fibers and migrasomes (PMID:41984101). It is incorporated into tetraspanin-enriched microdomains through lateral associations with other tetraspanins (CD9, CD81) and, via these partners, indirectly couples to integrins (alpha3beta1, alpha6beta1) rather than binding them directly (PMID:9360996, PMID:10229664). Palmitoylation at six juxtamembrane cysteines—installed by DHHC6 and removed by PPT1—is critical for TSPAN4 clustering and cholesterol recruitment, enabling the conversion of tetraspanin-enriched microdomains into the macrodomains required for migrasome formation; palmitoylation-deficient TSPAN4 acts as a dominant negative that suppresses migrasome biogenesis and disrupts left-right asymmetry and organ morphogenesis in zebrafish (PMID:41984101). Its large extracellular loop 2 confers membrane-curvature sensitivity and governs curvature-induced lateral interactions that enrich TSPAN4 in tubular membranes (PMID:38562622). Through these microdomains TSPAN4 modulates the surface fate of partner proteins: it associates with PD-L1 on melanoma cells and limits PD-L1 stability, lateral mobility, and surface availability for PD-1 engagement (PMID:41525200). TSPAN4 also engages signaling and cytoskeletal partners in disease contexts, stabilizing EGFR and sustaining MEK/ERK, STAT3, and AKT signaling to promote glioblastoma proliferation and invasion (PMID:39108703), and binding tropomyosin-1 to drive vascular smooth muscle cell phenotypic switching and neointimal formation (PMID:41004162). TGF-beta1 induces TSPAN4 expression via Smad2/3 to promote migrasome production in retinal pigmented epithelium during proliferative vitreoretinopathy (PMID:36494806).

Mechanistic history

Synthesis pass · year-by-year structured walk · 9 steps
  1. 1997 Medium

    Established that TSPAN4 is not an isolated membrane protein but a participant in the tetraspanin web, defining its membership in TM4SF-TM4SF and TM4SF-integrin complexes.

    Evidence Co-immunoprecipitation and two-color immunofluorescence in HT1080 cells showing association with CD9, CD81, and integrins alpha3beta1/alpha6beta1

    PMID:9360996

    Open questions at the time
    • Did not distinguish direct from indirect binding
    • No functional consequence of the complexes tested
  2. 1999 Medium

    Resolved the topology of TSPAN4-integrin association, showing the integrin link is indirect and bridged by other tetraspanins.

    Evidence Digitonin detergent immunoprecipitation across multiple cell lines disrupting tetraspan-tetraspan but not direct interactions

    PMID:10229664

    Open questions at the time
    • Which tetraspanin (CD81 vs CD151) provides the primary bridge not resolved
    • No structural basis for the lateral interaction
  3. 2012 Low

    Linked TSPAN4 expression to migratory cell populations during development, hinting at a role in cell migration before any mechanism was known.

    Evidence qRT-PCR and in situ hybridization in Xenopus laevis embryos

    PMID:22940433

    Open questions at the time
    • Expression correlation only, no functional perturbation of TSPAN4
    • No molecular mechanism addressed
  4. 2021 Medium

    Identified a GPCR partner, showing TSPAN4 can physically engage the histamine H4 receptor in a ligand-sensitive manner.

    Evidence Split-ubiquitin yeast two-hybrid, BRET, BiFC, and Co-IP in transfected cells

    PMID:34439793

    Open questions at the time
    • No effect on H4R G protein signaling, so functional purpose unclear
    • Interaction shown only in overexpression systems
  5. 2022 Medium

    Placed TSPAN4 downstream of TGF-beta1/Smad2/3 signaling as an inducible driver of migrasome production with pathological consequence.

    Evidence RPE cell models, siRNA knockdown, electron microscopy, and an in vivo proliferative vitreoretinopathy model

    PMID:36494806

    Open questions at the time
    • Mechanism of migrasome internalization not defined
    • Direct transcriptional regulation of TSPAN4 by Smad not shown
  6. 2024 Medium

    Connected TSPAN4 to oncogenic receptor signaling by showing it stabilizes EGFR and sustains downstream proliferative/invasive pathways.

    Evidence Co-IP, siRNA knockdown, western blot, in vitro proliferation/invasion assays, and xenografts in glioblastoma

    PMID:39108703

    Open questions at the time
    • Mechanism of EGFR stabilization (degradation vs trafficking) not defined
    • Direct vs tetraspanin-bridged EGFR contact not resolved
  7. 2024 Medium

    Provided a biophysical basis for TSPAN4 enrichment in curved membranes, assigning curvature sensing to extracellular loop 2.

    Evidence Micropipette aspiration and membrane tube pulling from giant plasma membrane vesicles with EC2 deletion mutants

    PMID:38562622

    Open questions at the time
    • Structural mechanism by which EC2 senses curvature unknown
    • Link between curvature sensing and full migrasome assembly not directly tested
  8. 2026 High

    Defined the post-translational switch controlling TSPAN4 microdomain assembly, identifying palmitoylation writer/eraser enzymes and cholesterol recruitment as the trigger for TEM-to-macrodomain conversion and migrasome formation.

    Evidence Palmitoylation and cysteine mutagenesis, DHHC6/PPT1 knockout/knockdown, live imaging, and zebrafish morphogenesis assays

    PMID:41984101

    Open questions at the time
    • Stoichiometry and dynamics of palmitoylation cycling in vivo not quantified
    • How cholesterol is recruited mechanistically not fully resolved
  9. 2026 Medium

    Revealed an immune-regulatory role at the membrane, showing TSPAN4 restrains PD-L1 surface availability and checkpoint engagement.

    Evidence Surface proximity biotinylation-MS, Co-IP, TSPAN4 knockdown, and PD-1/PD-L1 binding and T cell assays in melanoma

    PMID:41525200

    Open questions at the time
    • Mechanism by which TSPAN4 enhances PD-L1 degradation not defined
    • Interplay between TSPAN4 and CMTM6 at the molecular level unresolved

Open questions

Synthesis pass · forward-looking unresolved questions
  • How TSPAN4's diverse partner-specific roles (EGFR, PD-L1, TPM1, H4R) integrate with its core migrasome-organizing function under a single mechanistic framework remains open.
  • No unifying model linking microdomain assembly to partner-protein fate
  • Structural data on TSPAN4 complexes lacking
  • Whether partner regulation is migrasome-dependent untested

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0005198 structural molecule activity 2 GO:0098772 molecular function regulator activity 2 GO:0140299 molecular sensor activity 1
Localization
GO:0005886 plasma membrane 4
Complex memberships
tetraspanin-enriched microdomain

Evidence

Reading pass · 11 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
1997 NAG-2 (TSPAN4) co-immunoprecipitates with other TM4SF proteins (CD9 and CD81) and integrins (alpha3beta1 and alpha6beta1) in non-stringent detergent conditions, and co-localizes with CD81 on the surface of spread HT1080 cells, demonstrating its incorporation into specific TM4SF·TM4SF and TM4SF-integrin complexes. Co-immunoprecipitation, two-color immunofluorescence, expression cloning The Journal of biological chemistry Medium 9360996
1999 Under digitonin conditions that disrupt tetraspan-tetraspan interactions, NAG-2 (TSPAN4) does not form stable complexes with integrins, in contrast to CD81 and CD151, suggesting NAG-2 interacts with integrins indirectly through CD81 or CD151 rather than by direct binding. Immunoprecipitation in digitonin detergent from multiple cell lines The Biochemical journal Medium 10229664
2021 TSPAN4 physically interacts with the histamine H4 receptor (H4R), as confirmed by bioluminescence resonance energy transfer (BRET), bimolecular fluorescence complementation (BiFC), and co-immunoprecipitation in transfected cells. Histamine stimulation reduced the TSPAN4-H4R interaction, but TSPAN4 did not affect H4R-mediated G protein signaling. Split-ubiquitin membrane yeast two-hybrid, BRET, BiFC, co-immunoprecipitation Biomolecules Medium 34439793
2022 TGF-β1 increases TSPAN4 expression via the Smad2/3 signaling pathway in retinal pigmented epithelium (RPE) cells, leading to migrasome production. Migrasomes can be internalized by RPE cells and increase their migration and proliferation. TSPAN4-inhibited RPE cells show reduced ability to initiate experimental proliferative vitreoretinopathy (PVR). Ex vivo and in vitro RPE models, siRNA knockdown, electron microscopy, in vivo experimental PVR model Journal of nanobiotechnology Medium 36494806
2024 TSPAN4 interacts with EGFR and regulates its protein stability in glioblastoma cells. TSPAN4 knockdown disrupts the TSPAN4-EGFR interaction, destabilizes EGFR expression, and inactivates downstream MEK/ERK, STAT3, and AKT signaling pathways, inhibiting GBM cell proliferation and invasion in vitro and tumorigenicity in vivo. Co-immunoprecipitation, siRNA knockdown, overexpression, western blot, in vitro proliferation/invasion assays, in vivo xenograft iScience Medium 39108703
2025 TSPAN4 interacts with and influences the expression and localization of tropomyosin-1 (TPM1) in vascular smooth muscle cells, affecting cytoskeletal organization and driving phenotypic switching from contractile to synthetic phenotype. TSPAN4 deficiency in mice attenuated neointimal formation following carotid artery ligation. Co-immunoprecipitation, western blot, EdU assays, Transwell assays, TSPAN4-deficient mouse carotid ligation model Clinical science (London, England : 1979) Medium 41004162
2024 The extracellular loop 2 (EC2/LEL) of TSPAN4 contributes to its curvature sensitivity and curvature-induced lateral interactions. Deletion of EC2 had the most significant impact on TSPAN4 enrichment in tubular membranes and its interactions, as determined by micropipette aspiration with membrane tube pulling from giant plasma membrane vesicles. Micropipette aspiration, optical tweezers, confocal microscopy of giant plasma membrane vesicles expressing TSPAN4-GFP truncation mutants Biophysical reports Medium 38562622
2026 TSPAN4 is palmitoylated at six juxtamembrane cysteines, with DHHC6 and PPT1 identified as the main writer and eraser enzymes, respectively. This palmitoylation is critical for TSPAN4 clustering and cholesterol recruitment, enabling tetraspan-enriched microdomain (TEM) to macrodomain (TEMA) assembly required for migrasome formation. Palmitoylation-deficient TSPAN4 acts as a dominant negative, suppressing migrasome formation in cultured cells and zebrafish embryos, disrupting left-right asymmetry and organ morphogenesis. Palmitoylation assays, mutagenesis of cysteines, DHHC6/PPT1 knockout/knockdown, live cell imaging, zebrafish morphology assays The Journal of cell biology High 41984101
2026 TSPAN4 physically associates with PD-L1 on melanoma cell surfaces (colocalizing on migrasomes and retraction fibers) and negatively regulates PD-L1 protein levels by enhancing its degradation and restricting its lateral mobility at the plasma membrane. Loss of TSPAN4 stabilizes PD-L1, promotes its interaction with CMTM6, and increases PD-L1 surface availability for PD-1 binding, leading to more efficient immune checkpoint engagement. Cell surface proximity biotinylation coupled with mass spectrometry, co-immunoprecipitation, TSPAN4 knockdown, PD-1/PD-L1 binding assays, T cell functional assays Molecular oncology Medium 41525200
2012 TSPAN4 (as NAG-2/TM4SF7) is expressed in Xenopus laevis in migrating cranial neural crest cells, somites, developing eye, brain, and otic vesicles, suggesting a role in regulation of migration during development, consistent with its expression in cells with high migratory potential. Quantitative real-time PCR and in situ hybridization during Xenopus laevis embryonic development Gene expression patterns : GEP Low 22940433
2024 In migrating macrophages, TSPAN4 is a component of tetraspanin-enriched microdomains (TEMs) on retraction fibers and migrasomes. SCIMP (like TSPAN4) modulates retraction fiber and migrasome formation. Transmembrane TNF is delivered via SNARE-mediated carriers to the surfaces of retraction fibers and migrasomes, identifying retraction fibers as cytokine secretion sites. In vitro and in vivo macrophage imaging (mouse and zebrafish), TSPAN4 and SCIMP expression modulation, live cell microscopy bioRxivpreprint Low

Source papers

Stage 0 corpus · 74 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
1998 Selective enrichment of tetraspan proteins on the internal vesicles of multivesicular endosomes and on exosomes secreted by human B-lymphocytes. The Journal of biological chemistry 999 9685355
1996 CD9, CD63, CD81, and CD82 are components of a surface tetraspan network connected to HLA-DR and VLA integrins. European journal of immunology 329 8921952
1998 Regulation of endothelial cell motility by complexes of tetraspan molecules CD81/TAPA-1 and CD151/PETA-3 with alpha3 beta1 integrin localized at endothelial lateral junctions. The Journal of cell biology 227 9566977
1999 Selective tetraspan-integrin complexes (CD81/alpha4beta1, CD151/alpha3beta1, CD151/alpha6beta1) under conditions disrupting tetraspan interactions. The Biochemical journal 185 10229664
2000 The tetraspan molecule CD151, a novel constituent of hemidesmosomes, associates with the integrin alpha6beta4 and may regulate the spatial organization of hemidesmosomes. The Journal of cell biology 183 10811835
1996 Supramolecular complexes of MHC class I, MHC class II, CD20, and tetraspan molecules (CD53, CD81, and CD82) at the surface of a B cell line JY. Journal of immunology (Baltimore, Md. : 1950) 177 8816400
2001 Tetraspan microdomains distinct from lipid rafts enrich select peptide-MHC class II complexes. Nature immunology 172 11743588
1998 The tetraspan protein CD82 is a resident of MHC class II compartments where it associates with HLA-DR, -DM, and -DO molecules. Journal of immunology (Baltimore, Md. : 1950) 129 9759843
2019 The macrophage tetraspan MS4A4A enhances dectin-1-dependent NK cell-mediated resistance to metastasis. Nature immunology 120 31263276
2002 Clustering of MHC-peptide complexes prior to their engagement in the immunological synapse: lipid raft and tetraspan microdomains. Immunological reviews 103 12445271
1995 Molecular cloning of cDNA encoding a novel platelet-endothelial cell tetra-span antigen, PETA-3. Blood 90 7632941
1997 NAG-2, a novel transmembrane-4 superfamily (TM4SF) protein that complexes with integrins and other TM4SF proteins. The Journal of biological chemistry 85 9360996
2002 The tetraspan protein epithelial membrane protein-2 interacts with beta1 integrins and regulates adhesion. The Journal of biological chemistry 69 12189152
1997 CD9, a tetraspan transmembrane protein, renders cells susceptible to canine distemper virus. Journal of virology 68 8985321
1999 Rho-dependent regulation of cell spreading by the tetraspan membrane protein Gas3/PMP22. Molecular biology of the cell 64 10397775
2022 TSPAN4-positive migrasome derived from retinal pigmented epithelium cells contributes to the development of proliferative vitreoretinopathy. Journal of nanobiotechnology 62 36494806
2001 Mutations of peripheral myelin protein 22 result in defective trafficking through mechanisms which may be common to diseases involving tetraspan membrane proteins. Biochemistry 58 11583144
1995 A tetraspan membrane glycoprotein produced in the human intestinal epithelium and liver that can regulate cell density-dependent proliferation. The Journal of biological chemistry 57 7665614
2008 Cooperation between integrin alpha5 and tetraspan TM4SF5 regulates VEGF-mediated angiogenic activity. Blood 56 19036703
2015 Interaction of tetraspan(in) TM4SF5 with CD44 promotes self-renewal and circulating capacities of hepatocarcinoma cells. Hepatology (Baltimore, Md.) 55 25627085
2002 Tetraspan vesicle membrane proteins: synthesis, subcellular localization, and functional properties. International review of cytology 51 11893164
2004 The tetraspan protein EMP2 modulates the surface expression of caveolins and glycosylphosphatidyl inositol-linked proteins. Molecular biology of the cell 49 14978215
2000 Antibodies to CD9, a tetraspan transmembrane protein, inhibit canine distemper virus-induced cell-cell fusion but not virus-cell fusion. Journal of virology 48 10906209
2000 Function of tetraspan proteins in the myelin sheath. Current opinion in neurobiology 47 11084316
2006 Knockdown of the tetraspan protein epithelial membrane protein-2 inhibits implantation in the mouse. Developmental biology 44 16487956
2012 Tetraspan TM4SF5-dependent direct activation of FAK and metastatic potential of hepatocarcinoma cells. Journal of cell science 43 23077174
2003 The tetraspan protein EMP2 increases surface expression of class I major histocompatibility complex proteins and susceptibility to CTL-mediated cell death. Clinical immunology (Orlando, Fla.) 40 12763482
1996 Association of the tetraspan protein CD9 with integrins on the surface of S-16 Schwann cells. Journal of neurochemistry 39 8931484
1995 Platelet activation induced by a murine monoclonal antibody directed against a novel tetra-span antigen. British journal of haematology 38 7772522
2023 TSPAN4 and migrasomes in atherosclerosis regression correlated to myocardial infarction and pan-cancer progression. Cell adhesion & migration 37 36513632
1997 An antibody to the tetraspan membrane protein CD9 promotes neurite formation in a partially alpha3beta1 integrin-dependent manner. The Journal of neuroscience : the official journal of the Society for Neuroscience 37 9092597
2019 Circular RNA circ-TSPAN4 promotes lung adenocarcinoma metastasis by upregulating ZEB1 via sponging miR-665. Molecular genetics & genomic medicine 34 31573758
2007 The tetraspan protein EMP2 regulates expression of caveolin-1. The Journal of biological chemistry 34 17609206
1999 A novel rat tetraspan protein in cells of the oligodendrocyte lineage. Journal of neurochemistry 34 10582623
2013 Reversible folding of human peripheral myelin protein 22, a tetraspan membrane protein. Biochemistry 33 23639031
2003 Alterations in the Arf6-regulated plasma membrane endosomal recycling pathway in cells overexpressing the tetraspan protein Gas3/PMP22. Journal of cell science 31 12584243
2006 Synaptic tetraspan vesicle membrane proteins are conserved but not needed for synaptogenesis and neuronal function in Caenorhabditis elegans. Proceedings of the National Academy of Sciences of the United States of America 29 16698939
2005 Myelin tetraspan family proteins but no non-tetraspan family proteins are present in the ascidian (Ciona intestinalis) genome. The Biological bulletin 28 16110093
1997 Ligation of CD53/OX44, a tetraspan antigen, induces homotypic adhesion mediated by specific cell-cell interactions. Cellular immunology 27 9225004
2023 The tetraspan LHFPL5 is critical to establish maximal force sensitivity of the mechanotransduction channel of cochlear hair cells. Cell reports 25 36917610
2000 Tetraspan myelin protein PMP22 and demyelinating peripheral neuropathies: new facts and hypotheses. Glia 25 10625337
2021 Glycosylation limits forward trafficking of the tetraspan membrane protein PMP22. The Journal of biological chemistry 22 33933451
2012 Human tetraspanin transmembrane 4 superfamily member 4 or intestinal and liver tetraspan membrane protein is overexpressed in hepatocellular carcinoma and accelerates tumor cell growth. Acta biochimica et biophysica Sinica 21 22236579
2008 Expression of tetraspan protein CD63 activates protein-tyrosine kinase (PTK) and enhances the PTK-induced inhibition of ROMK channels. The Journal of biological chemistry 21 18211905
1999 CD82 (KAI1), a member of the tetraspan family, is expressed on early haemopoietic progenitor cells and up-regulated in distinct human leukaemias. British journal of haematology 21 10583248
2002 Transient activation of the c-Jun N-terminal kinase (JNK) activity by ligation of the tetraspan CD53 antigen in different cell types. European journal of biochemistry 19 11846804
2009 CUTI-1: A novel tetraspan protein involved in C. elegans CUTicle formation and epithelial integrity. PloS one 18 19357781
2001 Tetraspan protein CD151: a common target of mood stabilizing drugs? Neuropsychopharmacology : official publication of the American College of Neuropsychopharmacology 18 11682256
1998 CD63, a member of tetraspan transmembrane protein family, induces cellular spreading by reaction with monoclonal antibody on substrata. Biochemical and biophysical research communications 18 9618300
2007 Tetraspan proteins: regulators of renal structure and function. Current opinion in nephrology and hypertension 17 17565278
2024 TSPAN4 influences glioblastoma progression through regulating EGFR stability. iScience 16 39108703
2022 Coordinated regulation of TORC2 signaling by MCC/eisosome-associated proteins, Pil1 and tetraspan membrane proteins during the stress response. Molecular microbiology 16 35383382
2012 Expression of the tetraspanin family members Tspan3, Tspan4, Tspan5 and Tspan7 during Xenopus laevis embryonic development. Gene expression patterns : GEP 14 22940433
2024 Migrasome regulator TSPAN4 shapes the suppressive tumor immune microenvironment in pan-cancer. Frontiers in immunology 13 39723210
2018 Wnt Secretion Is Regulated by the Tetraspan Protein HIC-1 through Its Interaction with Neurabin/NAB-1. Cell reports 13 30428353
2009 The tetraspan protein Dni1p is required for correct membrane organization and cell wall remodelling during mating in Schizosaccharomyces pombe. Molecular microbiology 13 19627505
2021 N-terminus-independent activation of c-Src via binding to a tetraspan(in) TM4SF5 in hepatocellular carcinoma is abolished by the TM4SF5 C-terminal peptide application. Theranostics 12 34335982
2015 Tetraspan cargo adaptors usher GPI-anchored proteins into multivesicular bodies. Cell cycle (Georgetown, Tex.) 12 26505929
2025 TSPAN4+ fibroblasts coordinate metastatic niche assembly through migrasome-driven metabolic reprogramming and stromal-immune crosstalk in pancreatic adenocarcinoma. Frontiers in immunology 9 40443671
2021 Identification of TSPAN4 as Novel Histamine H4 Receptor Interactor. Biomolecules 9 34439793
2010 Generation of anti-NAG-2 mAb from patients' memory B cells: implications for a novel therapeutic strategy in systemic sclerosis. International immunology 8 20207716
2004 Tetraspan and beta-1 integrins expression pattern of the epithelial lung adenocarcinoma cell line A549 and its sensitivity to divalent cations. Cytometry. Part B, Clinical cytometry 8 15221867
1997 Chromosomal localization of the human urothelial "tetraspan" gene, UPK1B, to 3q13.3-q21 and detection of a TaqI polymorphism. Genomics 7 9073521
2023 Tetraspan MS4A6D is a coreceptor of MHC class II antigen (MHC-II) that promotes macrophages-derived inflammation. Molecular immunology 5 37429063
2015 Regulation of FAK Activity by Tetraspan Proteins: Potential Clinical Implications in Cancer. Critical reviews in oncogenesis 5 27279237
2011 Rewiring integrin-mediated signaling and cellular response with the peripheral myelin protein 22 and epithelial membrane protein 2 components of the tetraspan web. Investigative ophthalmology & visual science 4 21421883
2016 Characterization of the Tetraspan Junctional Complex (4JC) superfamily. Biochimica et biophysica acta. Biomembranes 3 27916633
2026 Dynamic crosstalk between Tspan4+ macrophage subsets and MSCs via migrasomes orchestrates fracture repair. Frontiers in cell and developmental biology 1 41584843
2025 TSPAN4 controls vascular smooth muscle cell phenotypic switching and intimal hyperplasia by targeting TPM1-regulated cytoskeletal organization. Clinical science (London, England : 1979) 1 41004162
2024 Extracellular domain 2 of TSPAN4 governs its functions. Biophysical reports 1 38562622
2024 Exploring TSPAN4 promoter methylation as a diagnostic biomarker for tuberculosis. Frontiers in genetics 1 38680421
2026 Cell surface interactome analysis identifies TSPAN4 as a negative regulator of PD-L1 in melanoma. Molecular oncology 0 41525200
2026 Tspan4+ fibroblasts facilitate the development of NECSO in myocardial ischemia reperfusion through migrasomes-mediated Tnf-α autocrine and cardiomyocytes aldosterone generation. Biochemical pharmacology 0 41887336
2026 Palmitoylation of Tspan4 is essential for migrasome formation. The Journal of cell biology 0 41984101

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