{"gene":"FPR1","run_date":"2026-06-09T23:54:44","timeline":{"discoveries":[{"year":1994,"finding":"FMLP binding to FPR1 (a seven-transmembrane G-protein-coupled receptor) activates Ras and Raf-1 in human neutrophils through a pertussis toxin-sensitive Gi2 protein linkage, independent of protein kinase C, leading to MEK and MAP kinase activation.","method":"Immunoprecipitation of Raf-1 kinase activity, [32P]GTP-labeling of Ras in intact and electropermeabilized neutrophils, pertussis toxin inhibition, dibutyryl cAMP inhibition studies","journal":"The Journal of Clinical Investigation","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods (kinase assay, GTP-loading, pertussis toxin, PKC inhibitors) in a focused mechanistic study replicated across signaling nodes","pmids":["8040337"],"is_preprint":false},{"year":1994,"finding":"The NH2-terminal extracellular region of FPR is NOT required for plasma membrane trafficking or high-affinity N-formylpeptide binding (in contrast to C5aR); replacing FPR's NH2-terminus with C5aR sequence still permitted normal surface expression and ligand binding.","method":"Chimeric receptor mutagenesis, cell surface expression assays, radioligand binding assays","journal":"The Journal of Biological Chemistry","confidence":"High","confidence_rationale":"Tier 1 / Strong — reconstitution with chimeric mutagenesis and direct binding assays; clear positive and negative controls","pmids":["8106386"],"is_preprint":false},{"year":1998,"finding":"FMLP-stimulated FPR1 activation in human neutrophils requires p38 MAP kinase for chemotaxis and superoxide generation; pharmacological inhibition of p38 (SB20358) markedly suppressed both responses, whereas p44/42 MAP kinase inhibition (PD98059) did not.","method":"Kinase phosphorylation analysis, selective kinase inhibitors (SB20358, PD98059), superoxide generation assay, chemotaxis assay in human neutrophils","journal":"Journal of Immunology","confidence":"High","confidence_rationale":"Tier 2 / Strong — pharmacological dissection with selective inhibitors across multiple functional readouts in primary human cells","pmids":["9469462"],"is_preprint":false},{"year":1999,"finding":"Mouse FPR1 and a second lower-affinity receptor (FPR2) together account for the biphasic fMLF concentration-chemotaxis curve in mouse neutrophils; FPR knockout neutrophils lose the high-sensitivity optimum, establishing that FPR1 mediates responses to low concentrations of N-formylpeptide.","method":"Calcium flux and chemotaxis assays in HEK293 cells transfected with FPR or FPR2, comparison of wild-type versus FPR-knockout mouse neutrophils","journal":"The Journal of Experimental Medicine","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic knockout combined with transfected cell reconstitution and functional dose-response analysis","pmids":["10477558"],"is_preprint":false},{"year":2001,"finding":"Amyloid-β42 acts as a chemotactic agonist at FPRL1 (FPR2/ALX), not FPR1; FPR1-expressing cells do not respond, establishing receptor selectivity for this ligand.","method":"Chemotaxis assays in HL-60 cells stably expressing FPR1 or FPRL1; receptor-specific functional readouts","journal":"The Journal of Neuroscience","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — transfected cell lines with functional chemotaxis readout, single lab study","pmids":["11160457"],"is_preprint":false},{"year":2002,"finding":"FPR1 mediates fMLF-induced NADPH oxidase-dependent superoxide production in mouse neutrophils; FPR1-deficient neutrophils show markedly reduced superoxide at low fMLF concentrations, but a second Gi-coupled receptor (likely FPR2) maintains oxidase activation at high concentrations.","method":"Superoxide production assay comparing FPR+/+ and FPR−/− mouse neutrophils; pharmacological inhibition with pertussis toxin","journal":"Cellular Immunology","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic knockout model with clear dose-response comparison and pharmacological confirmation of Gi coupling","pmids":["12470609"],"is_preprint":false},{"year":2003,"finding":"Annexin A1 (AnxA1) and its mimetic peptide Ac2-26 exert anti-adhesive effects on leukocytes partly through FPR1 and partly through ALXR (FPR2); in FPR-deficient mice, Ac2-26 retains ~50% inhibitory activity blocked by the pan-FPR antagonist Boc2, and FPR-deficient neutrophils express functional ALXR.","method":"In vivo ischemia/reperfusion intravital microscopy in FPR-knockout mice; in vitro neutrophil activation at high fMLP concentrations; RT-PCR and protein detection for ALXR","journal":"Blood","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic KO mouse model combined with in vivo intravital readout and in vitro pharmacological validation","pmids":["12560218"],"is_preprint":false},{"year":2005,"finding":"Listeria monocytogenes-derived N-formylpeptides preferentially activate FPR1 (~100-fold more potent than FPRL1), whereas human mitochondria-derived N-formylpeptides (fMLKLIV, fMMYALF, fMFADRW) are equally potent agonists of both FPR1 and FPRL1, with EC50 values in the 10–160 nM range.","method":"Intracellular calcium mobilization (Fura-2) in HL-60 cell lines stably expressing FPR1, FPRL1, or FPRL2; chemotaxis assays","journal":"European Journal of Immunology","confidence":"High","confidence_rationale":"Tier 2 / Strong — receptor-expressing stable cell lines, quantitative dose-response across multiple peptides and receptors","pmids":["16025565"],"is_preprint":false},{"year":2005,"finding":"The uPAR-derived SRSRY peptide activates FPR1 to induce cell migration, F-actin polarization, and cross-talk with the vitronectin receptor αvβ5; fMLP competition experiments and FPR1 pathway dependence established FPR1 as the transducing receptor for SRSRY-stimulated cytoskeletal rearrangement.","method":"Competitive ligand binding, migration assays on vitronectin-coated filters, F-actin immunostaining, PKC activity and ERK1/2 phosphorylation, αvβ5 co-immunoprecipitation","journal":"The Journal of Biological Chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple signaling readouts and competitive displacement, single lab","pmids":["15866865"],"is_preprint":false},{"year":2005,"finding":"Formylpeptide receptor FPR1 mediates chemotaxis, proliferation, and VEGF production in human glioblastoma cells (U-87); FPR1 siRNA knockdown substantially reduced xenograft tumor volume, and necrotic glioblastoma cells release endogenous FPR1 agonist(s).","method":"RT-PCR, chemotaxis assay, siRNA knockdown, xenograft nude mouse model, VEGF ELISA, basophil leukemia cell FPR activation assay","journal":"Journal of the National Cancer Institute","confidence":"High","confidence_rationale":"Tier 2 / Strong — loss-of-function siRNA with xenograft phenotype plus multiple functional readouts (chemotaxis, proliferation, VEGF) in same study","pmids":["15928303"],"is_preprint":false},{"year":2005,"finding":"An annexin AI peptide (Ac9-25) activates neutrophil NADPH oxidase through FPR1 (not FPRL1); the inhibitory signal generated by the same peptide on oxidase activity is transduced by a separate, unidentified receptor distinct from FPR1 and FPRL1.","method":"Receptor antagonists/inhibitors, receptor desensitization experiments, FPR1/FPRL1-transfected cell lines, superoxide anion release assay","journal":"Journal of Leukocyte Biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — transfected cell reconstitution plus pharmacological dissection with multiple antagonists identifying two distinct signaling arms","pmids":["15951351"],"is_preprint":false},{"year":2007,"finding":"FPR1 activation by fMLF in glioblastoma cells (U87) drives production of both VEGF and IL-8 (CXCL8); FPR1 siRNA abolished production of both angiogenic factors and reduced tumor angiogenesis in vivo.","method":"FPR1 siRNA transfection, fMLF stimulation, RT-PCR and ELISA for VEGF and IL-8, nude mouse xenograft angiogenesis assessment","journal":"Journal of Neuro-oncology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — siRNA loss-of-function with multiple angiogenic factor readouts and in vivo confirmation, single lab","pmids":["17611713"],"is_preprint":false},{"year":2008,"finding":"FPR1 expressed on glioblastoma stem cells (CD133+ GSCs from U87) mediates calcium flux and VEGF production in response to fMLF stimulation.","method":"Flow cytometry for CD133, calcium flux assay, VEGF measurement, xenograft tumor formation","journal":"The Journal of Pathology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — functional receptor assays (calcium flux) in sorted stem cell subpopulation, single lab","pmids":["18523971"],"is_preprint":false},{"year":2008,"finding":"p53 binds to the FPR1 promoter region and suppresses FPR1 expression in glioblastoma cells; DNA methyltransferase inhibition (5-Aza-2'-deoxycytidine) promotes glioblastoma differentiation and reduces FPR1 expression via a p53-dependent mechanism.","method":"Chromatin immunoprecipitation (ChIP) for p53 binding to FPR1 promoter, methylation-specific PCR, p53 overexpression, flow cytometry, nude mouse xenograft","journal":"Carcinogenesis","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — ChIP demonstrates direct p53-FPR1 promoter binding; supported by overexpression experiments, single lab","pmids":["19037090"],"is_preprint":false},{"year":2009,"finding":"FPR1 is identified as the receptor for the Staphylococcus aureus protein FLIPr-like, which inhibits FPR1-mediated neutrophil calcium mobilization and chemotaxis; the second N-terminal phenylalanine of FLIPr-like is required specifically for FPR1 inhibition.","method":"Neutrophil calcium mobilization assay, chemotaxis assay, transfected cell binding studies, mutagenesis of FLIPr-like N-terminal residues","journal":"Journal of Immunology","confidence":"High","confidence_rationale":"Tier 1 / Strong — mutagenesis of inhibitor combined with receptor-transfected cell assays and functional neutrophil readouts","pmids":["19846866"],"is_preprint":false},{"year":2010,"finding":"FPR1 expression confers increased motility and invasive tumor phenotype to glioblastoma cells; FPR1-overexpressing clones formed more rapidly growing and invasive xenograft tumors, and serum-derived FPR1 agonist activity stimulated FPR1-dependent cell motility.","method":"Single-cell cloning, flow cytometry, RT-PCR, wound-healing motility assay, calcium flux, nude mouse xenograft with subcutaneous implantation","journal":"British Journal of Cancer","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — gain-of-function overexpression plus isogenic clonal comparison with in vivo confirmation, single lab","pmids":["20197768"],"is_preprint":false},{"year":2010,"finding":"FPR1 cross-talks with EGFR and TrkA in monocytes: FPR1 inhibition (cyclosporin H) prevents EGFR and TrkA phosphorylation by their own ligands, and FPR1 siRNA suppresses EGF- and NGF-mediated ERK phosphorylation, ROS production, MMP-9 production, and CD11b upregulation.","method":"Receptor-specific inhibitors, siRNA knockdown of each receptor, immunoblotting for receptor phosphorylation and ERK, ROS and MMP-9 measurements, CD11b expression by flow cytometry","journal":"Cellular Signalling","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — siRNA knockdown plus pharmacological inhibitors with multiple functional readouts, single lab","pmids":["20566383"],"is_preprint":false},{"year":2010,"finding":"Mitochondrial degradation products (formylated mitochondrial peptides) activate human neutrophils exclusively through FPR1 (high-affinity receptor); anti-FPR1 antibody completely blocked calcium responses, whereas anti-FPRL1 antibody did not.","method":"Cytosolic calcium ([Ca]i) assay with antibody blockade of FPR1 and FPRL1, chemotaxis in trans-wells, oxidative burst assay","journal":"The Journal of Trauma","confidence":"High","confidence_rationale":"Tier 2 / Strong — antibody-mediated receptor blockade with complete inhibition, multiple functional readouts (Ca2+ flux, chemotaxis, oxidative burst)","pmids":["20539176"],"is_preprint":false},{"year":2011,"finding":"FPR1 mediates fMLP-induced osteoblastic differentiation of human bone marrow mesenchymal stem cells via a phospholipase C/D–Ca2+–CaMKII–ERK–CREB signaling pathway; FPR1 expression is specifically upregulated during osteogenesis, and the FPR1-selective antagonist cyclosporin H blocks fMLP-stimulated osteogenesis.","method":"qPCR, flow cytometry, cyclosporin H antagonism, phospho-specific immunoblotting, osteogenic/adipogenic differentiation assays, zebrafish and rabbit in vivo bone formation models","journal":"The Journal of Biological Chemistry","confidence":"High","confidence_rationale":"Tier 2 / Strong — pharmacological antagonist blocks pathway with multiple orthogonal signaling readouts and in vivo models","pmids":["21372136"],"is_preprint":false},{"year":2012,"finding":"Genetic ablation of Fpr1 in mice protects against cigarette smoke-induced lung emphysema by preventing neutrophil and macrophage recruitment to the lung; the FPR1 antagonist cyclosporin H similarly attenuated acute inflammatory responses.","method":"Fpr1 knockout mouse model, histological assessment, inflammatory cell counts in BAL, gene expression profiling, pharmacological antagonism with cyclosporin H","journal":"American Journal of Respiratory Cell and Molecular Biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic KO with pharmacological confirmation and histological/cellular phenotype quantification","pmids":["22461430"],"is_preprint":false},{"year":2012,"finding":"FPR1 activation by annexin A1 (ANXA1) transactivates EGFR in glioblastoma cells to promote chemotaxis, invasion, growth, and angiogenic factor production.","method":"Cited in review context (PMID 22863814); mechanistic support from referenced experimental work showing FPR1-EGFR transactivation","journal":"International Immunopharmacology","confidence":"Low","confidence_rationale":"Tier 4 / Weak — described in a review abstract without primary experimental detail presented in this abstract","pmids":["22863814"],"is_preprint":false},{"year":2013,"finding":"In acute lung injury (ALI) induced by aerosolized LPS, FPR1 (but not FPR2) is required for neutrophil infiltration into all lung compartments; Fpr1-/- mice and pharmacological FPR1 blockade reduced alveolar, interstitial, and intravascular neutrophil counts and attenuated lung edema.","method":"Fpr1-/- and Fpr2-/- mouse comparison, LPS aerosol ALI model, BAL cell counts, histology, specific receptor antagonists","journal":"Journal of Innate Immunity","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic KO with pharmacological confirmation across multiple lung compartments","pmids":["23860188"],"is_preprint":false},{"year":2014,"finding":"FPR1 is the receptor for annexin A1 on SJS/TEN keratinocytes; annexin A1 secreted by drug-stimulated PBMCs binds FPR1 (overexpressed in SJS/TEN keratinocytes) to induce necroptosis via RIP1/RIP3 complex formation.","method":"Mass spectrometry identification of annexin A1, anti-annexin A1 antibody depletion, FPR1 expression by immunostaining, RIP1/RIP3 pathway analysis, mouse SJS/TEN model with necroptosis inhibitor","journal":"Science Translational Medicine","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods (MS, antibody depletion, pathway genetic dissection, mouse model) establishing AnxA1-FPR1-necroptosis axis","pmids":["25031270"],"is_preprint":false},{"year":2014,"finding":"FAM19A4 (TAFA4) is a novel agonist ligand of FPR1; binding established by receptor internalization assays, radioligand competition binding, and receptor blockade; FAM19A4/FPR1 signaling promotes macrophage migration, phagocytosis, and Akt phosphorylation.","method":"Receptor internalization assay, radioligand binding assay, receptor blockade, macrophage chemotaxis, phagocytosis assay, Akt phosphorylation by immunoblot","journal":"Cellular & Molecular Immunology","confidence":"High","confidence_rationale":"Tier 2 / Strong — three independent binding methods (internalization, radioligand competition, blockade) plus functional downstream signaling readouts","pmids":["25109685"],"is_preprint":false},{"year":2014,"finding":"uPAR co-localizes and co-immunoprecipitates with FPR1 at the cell surface; uPAR expression drives FPR1/β1-integrin co-localization that is further enhanced by the FPR1 ligand WKYMVm, and uPAR-dependent cell migration requires intact uPAR–FPR1 interaction.","method":"Co-immunoprecipitation, confocal co-localization, siRNA knockdown of uPAR, antibody blocking, migration assays in uPAR-transfected HEK293 cells","journal":"PLoS ONE","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — co-IP and siRNA with functional migration readout, single lab","pmids":["24466048"],"is_preprint":false},{"year":2016,"finding":"FPR1 activation by fMLP in neuroblastoma cells induces intracellular calcium mobilization and activates MAPK/Erk, PI3K/Akt, and p38-MAPK pathways; FPR1 shRNA knockdown delays xenograft tumor development, while FPR1 overexpression promotes augmented tumorigenesis.","method":"Calcium mobilization assay, phospho-specific immunoblotting, cyclosporin H antagonism, shRNA knockdown and FPR1 cDNA overexpression with nude mouse xenograft","journal":"BMC Cancer","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal gain/loss-of-function with xenograft phenotype and pharmacological validation of signaling pathways","pmids":["27432059"],"is_preprint":false},{"year":2016,"finding":"Exogenous CO (CORM-2) inhibits FPR1-mediated neutrophil infiltration by promoting FPR1 internalization through inhibition of p38 MAPK, but not through GRK2.","method":"Affymetrix gene chip analysis, under-agarose migration assay, FPR1 internalization studies, p38 MAPK inhibition vs. GRK2 inhibition comparisons","journal":"Oncotarget","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — mechanistic dissection of FPR1 internalization via p38 vs. GRK2 with functional migration readout, single lab","pmids":["27144520"],"is_preprint":false},{"year":2019,"finding":"FPR1 is the direct receptor on immune cells exploited by Yersinia pestis for type III secretion system effector translocation; the Y. pestis needle cap protein LcrV binds FPR1, and Fpr1-deficient mice show increased survival; the FPR1R190W allele in humans protects neutrophils from Y. pestis destruction.","method":"Direct binding of LcrV to FPR1, Fpr1-/- mouse infection model (survival, antibody responses), ex vivo neutrophil translocation assay with FPR1R190W variant cells","journal":"Nature","confidence":"High","confidence_rationale":"Tier 2 / Strong — direct protein binding plus genetic KO infection model plus human variant functional assay across multiple orthogonal approaches","pmids":["31534221"],"is_preprint":false},{"year":2019,"finding":"FPR1 in the gut mediates commensal bacterium (LGG)-induced ROS production and MAPK1 phosphorylation in myenteric neurons; FPR1-knockout mice fail to show LGG-induced ROS production, ChAT upregulation, or increased GI motility.","method":"FPR1-KO mouse model, fluorescence in situ hybridization for FPR1 in myenteric plexi, immunostaining/immunoblots for ROS and p-MAPK1, GI transit/motility measurements, LGG gavage","journal":"Gastroenterology","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic KO with multiple orthogonal readouts (molecular, cellular, physiological) and bacterial adhesion-mutant controls","pmids":["30930024"],"is_preprint":false},{"year":2020,"finding":"FPR1 on dendritic cells is required for ANXA1-mediated immunogenic cell death signaling after anthracycline chemotherapy; tumors lacking ANXA1 or growing in Fpr1-/- mice show deficient DC- and T-lymphocyte-mediated anticancer immunity, and FPR1 loss-of-function is associated with earlier breast cancer onset.","method":"Fpr1-/- mouse tumor models, DC/T-cell functional assays, pIC (TLR3 ligand) rescue experiments, carcinogen-induced tumor model in Fpr1-/- mice","journal":"Cancer Discovery","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic KO model with multiple immune cell functional assays, pharmacological rescue (pIC), and carcinogenesis model","pmids":["33046534"],"is_preprint":false},{"year":2020,"finding":"FPR1 deficiency (fpr1-/-) protects mice from bleomycin-induced pulmonary fibrosis by preventing neutrophil recruitment to the lung; adoptive transfer established that the neutrophil recruitment defect is intrinsic to fpr1-/- neutrophils. FPR1 deficiency did not affect renal or hepatic fibrosis, demonstrating tissue-specific function.","method":"Fpr1-/- mouse bleomycin model, neutrophil adoptive transfer, histology, cell counts, gene expression analysis","journal":"JCI Insight","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic KO with adoptive transfer establishing cell-intrinsic mechanism, tissue specificity confirmed across three organ models","pmids":["32102985"],"is_preprint":false},{"year":2020,"finding":"FPR1 modulates NLRP3 inflammasome signaling and NF-κB nuclear translocation in bronchiolitis obliterans syndrome; Fpr1 KO mice show greater reduction in NF-κB, NLRP3, and MAPK pathway activation than IL-1β/IL-18 or Casp-1 KO mice.","method":"Transgenic KO mouse model of allogeneic heterotopic tracheal transplantation BOS, molecular pathway analysis (NF-κB, NLRP3, MAPK), TUNEL apoptosis assay, immunohistochemistry","journal":"International Journal of Molecular Sciences","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic KO with pathway analysis; comparative KO design is informative but mechanistic link is correlative","pmids":["32244997"],"is_preprint":false},{"year":2022,"finding":"High glucose conditions impair FPR-mediated chemotaxis signaling in diabetic neutrophils, delaying neutrophil trafficking in wounds of Lepr(db/db) type 2 diabetic mice; auxiliary CCL3 receptor engagement overrides the FPR signaling impairment.","method":"Diabetic mouse model (Lepr db/db), in vitro glucose exposure of neutrophils, chemotaxis assays, in vivo neutrophil wound trafficking measurement, CCL3 rescue experiment","journal":"eLife","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — diabetic mouse model with in vitro mechanistic confirmation and functional rescue, single lab","pmids":["35112667"],"is_preprint":false},{"year":2022,"finding":"FPR1 facilitates splenocyte migration into ischemic brain tissue and promotes proinflammatory cytokine production after stroke; Fpr1-/- mice showed reduced peripheral monocyte/neutrophil infiltration into ischemic brain and improved neurological outcomes.","method":"Transient focal brain ischemia in Fpr1-/- mice, splenocyte migration assays in vivo and in vitro, cFLFLF FPR1 antagonist treatment, cytokine measurements, neurological scoring","journal":"Theranostics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic KO combined with pharmacological antagonism and functional migration assays, single lab","pmids":["35547761"],"is_preprint":false},{"year":2013,"finding":"FPR1 pepducins (lipidated peptides based on the third intracellular loop of FPR1) do not activate FPR1 but instead potently inhibit FPR2-mediated neutrophil superoxide production and granule mobilization; the FPR2-specific K231 residue (vs. FPR1's Q231) determines pepducin activity.","method":"Pepducin receptor selectivity assay in FPR1/FPR2-transfected cells and human neutrophils, amino acid substitution studies of third intracellular loop, superoxide production and granule mobilization assays","journal":"Biochimica et Biophysica Acta","confidence":"Medium","confidence_rationale":"Tier 1 / Moderate — mutagenesis of specific residues plus transfected cell reconstitution, single lab; finding is primarily about FPR2 with FPR1 as negative control","pmids":["23562731"],"is_preprint":false},{"year":2020,"finding":"The small compound RE-04-001 is a highly potent FPR1-specific agonist (EC50 ~1 nM for NADPH oxidase activation) that displays biased signaling: strongly activates PLC-PIP2-Ca2+ and ERK1/2 pathways but shows minimal β-arrestin recruitment compared to fMLF.","method":"FPR1/FPR2 receptor-expressing cells and human neutrophils, Ca2+ flux assay, superoxide production, ERK phosphorylation, β-arrestin recruitment assay, chemotaxis assay, receptor-selective antagonist confirmation","journal":"Journal of Leukocyte Biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple signaling pathway readouts with biased agonism characterization, single lab","pmids":["33040403"],"is_preprint":false}],"current_model":"FPR1 is a seven-transmembrane Gi-coupled G protein-coupled receptor on phagocytic leukocytes (and some other cell types) that binds N-formylated bacterial and mitochondrial peptides (including fMLF), as well as endogenous ligands such as annexin A1 (ANXA1), FAM19A4/TAFA4, and the Y. pestis needle-cap protein LcrV, to activate Gi2-Ras-Raf-MEK-MAPK signaling, PLC-Ca2+ mobilization, p38-MAPK, and PI3K-Akt cascades, driving neutrophil chemotaxis, NADPH oxidase-dependent superoxide production, degranulation, cytokine/VEGF/IL-8 production, and—in certain cancer and stem cell contexts—FPR1-EGFR transactivation; FPR1 also acts as a pattern-recognition receptor facilitating innate immune cell recruitment to sites of infection, tissue damage, and fibrosis, with loss-of-function conferring protection from pulmonary fibrosis, emphysema, and plague infection."},"narrative":{"mechanistic_narrative":"FPR1 is a seven-transmembrane, pertussis-toxin-sensitive Gi2-coupled G-protein-coupled receptor on neutrophils and other leukocytes that detects N-formylated peptides of bacterial and mitochondrial origin and converts that recognition into chemotaxis and antimicrobial effector function [PMID:8040337, PMID:10477558, PMID:20539176]. Ligand engagement by fMLF activates a Gi2-Ras-Raf-1-MEK-MAPK cascade, with parallel requirement for p38 MAP kinase, to drive both directional migration and NADPH oxidase-dependent superoxide production [PMID:8040337, PMID:9469462, PMID:12470609]. FPR1 is the high-affinity receptor that confers neutrophil responses to low concentrations of N-formylpeptide, including peptides derived from Listeria and from human mitochondria, while a lower-affinity receptor (FPR2) handles high-concentration responses [PMID:10477558, PMID:16025565, PMID:20539176]. The receptor recognizes a broad ligand repertoire beyond formyl peptides: the anti-inflammatory protein annexin A1 and its peptides act through FPR1 to modulate leukocyte adhesion and, in keratinocytes, to drive RIP1/RIP3-dependent necroptosis [PMID:12560218, PMID:25031270]; FAM19A4/TAFA4 is an agonist that promotes macrophage migration, phagocytosis, and Akt phosphorylation [PMID:25109685]; and the uPAR-derived SRSRY peptide engages FPR1 to coordinate cytoskeletal rearrangement and integrin cross-talk [PMID:15866865, PMID:24466048]. Mechanistically the receptor is exploited by pathogens — the Staphylococcus aureus protein FLIPr-like antagonizes FPR1, and the Yersinia pestis needle-cap protein LcrV binds FPR1 to enable type III secretion, with loss-of-function variants protecting against plague [PMID:19846866, PMID:31534221]. Through its role in recruiting innate immune cells, FPR1 drives neutrophil/macrophage influx underlying cigarette-smoke emphysema, LPS acute lung injury, bleomycin pulmonary fibrosis, and post-ischemic brain inflammation, such that genetic ablation is protective in these settings [PMID:22461430, PMID:23860188, PMID:32102985, PMID:35547761]. In tumor and stem-cell contexts FPR1 promotes glioblastoma and neuroblastoma motility, proliferation, and VEGF/IL-8 production and supports anthracycline-induced immunogenic cell death via dendritic-cell ANXA1 sensing [PMID:15928303, PMID:27432059, PMID:33046534].","teleology":[{"year":1994,"claim":"Established the proximal signaling logic of FPR1 by showing that formyl peptide binding couples through Gi2 to the Ras-Raf-MEK-MAPK module independent of PKC, defining how an immune chemoattractant receptor engages a canonical mitogenic cascade.","evidence":"Raf-1 kinase immunoprecipitation, Ras GTP-loading, pertussis toxin and PKC-inhibitor dissection in human neutrophils","pmids":["8040337"],"confidence":"High","gaps":["Did not map which intracellular receptor regions couple to Gi2","Downstream functional consequences (chemotaxis vs. oxidase) not separated at this stage"]},{"year":1994,"claim":"Defined receptor architecture by showing the extracellular N-terminus is dispensable for surface trafficking and high-affinity ligand binding, distinguishing FPR1's binding determinants from the related C5a receptor.","evidence":"Chimeric FPR/C5aR receptor mutagenesis with surface expression and radioligand binding assays","pmids":["8106386"],"confidence":"High","gaps":["Did not identify the actual transmembrane/loop residues forming the ligand pocket","No structural model of the bound peptide"]},{"year":1998,"claim":"Showed that distinct MAPK arms serve distinct effector outputs, with p38 (not p44/42) required for both chemotaxis and superoxide generation, refining which kinase branch drives FPR1 functional responses.","evidence":"Selective kinase inhibitors (SB20358, PD98059) with chemotaxis and superoxide readouts in human neutrophils","pmids":["9469462"],"confidence":"High","gaps":["Did not resolve how Gi2-Ras output integrates with p38 activation","Upstream p38 activators downstream of FPR1 unidentified"]},{"year":1999,"claim":"Genetic knockout established FPR1 as the high-sensitivity formyl peptide receptor responsible for the low-concentration optimum of neutrophil chemotaxis, with FPR2 covering high-concentration responses.","evidence":"Calcium flux and chemotaxis in transfected HEK293 cells and FPR-knockout versus wild-type mouse neutrophils","pmids":["10477558"],"confidence":"High","gaps":["Did not define the structural basis of the affinity difference between FPR1 and FPR2","Biphasic response mechanism only inferred functionally"]},{"year":2002,"claim":"Confirmed via knockout that FPR1 transduces fMLF-induced NADPH oxidase activation at low ligand concentrations, linking the high-affinity receptor specifically to respiratory burst.","evidence":"Superoxide assays in FPR+/+ versus FPR-/- mouse neutrophils with pertussis toxin","pmids":["12470609"],"confidence":"High","gaps":["Did not identify the assembly steps connecting FPR1 to the oxidase complex"]},{"year":2005,"claim":"Expanded the ligand repertoire and defined receptor selectivity, showing FPR1 strongly prefers bacterial Listeria formyl peptides while mitochondrial formyl peptides activate both FPR1 and FPR2, framing FPR1 as a sensor of both microbial and host-damage signals.","evidence":"Calcium mobilization and chemotaxis in HL-60 lines stably expressing FPR1, FPRL1, or FPRL2 across multiple peptides","pmids":["16025565"],"confidence":"High","gaps":["Did not test these peptides in primary cells or in vivo","Physiological source/concentration of mitochondrial peptides not established"]},{"year":2005,"claim":"Showed FPR1 mediates non-formyl ligand signaling, including the annexin A1 peptide-driven oxidase activation and the uPAR SRSRY peptide-driven cytoskeletal/integrin cross-talk, broadening the receptor's role beyond pathogen sensing.","evidence":"Receptor-transfected cell lines, antagonist/desensitization studies, superoxide assays, migration on vitronectin, F-actin imaging and αvβ5 co-IP","pmids":["15951351","15866865"],"confidence":"High","gaps":["Distinct inhibitory annexin A1 receptor remained unidentified","Direct binding of SRSRY to FPR1 inferred from competition, not co-crystal"]},{"year":2005,"claim":"Identified a pathogenic role for FPR1 in cancer, showing it drives glioblastoma chemotaxis, proliferation, and VEGF production and that tumor cells release endogenous FPR1 agonists, establishing autocrine/necrotic-ligand signaling in tumors.","evidence":"siRNA knockdown, xenograft tumor model, VEGF ELISA, chemotaxis and necrotic-cell agonist assays in U-87 cells","pmids":["15928303"],"confidence":"High","gaps":["Endogenous tumor-derived FPR1 agonist not chemically identified","Whether effects are cell-intrinsic versus stroma-mediated not resolved"]},{"year":2007,"claim":"Extended tumor signaling to angiogenesis by showing FPR1 controls both VEGF and IL-8 output to promote glioblastoma vascularization.","evidence":"FPR1 siRNA, fMLF stimulation, VEGF/IL-8 RT-PCR and ELISA, xenograft angiogenesis assessment","pmids":["17611713"],"confidence":"Medium","gaps":["Single tumor model (U87)","Signaling intermediates linking FPR1 to angiogenic transcription not defined"]},{"year":2008,"claim":"Linked FPR1 expression control to tumor suppressor regulation, showing p53 directly binds the FPR1 promoter to repress expression in glioblastoma.","evidence":"ChIP for p53 at the FPR1 promoter, methylation-specific PCR, p53 overexpression, xenograft","pmids":["19037090"],"confidence":"Medium","gaps":["Single lab/cell context","Mechanism connecting DNA methylation to p53-dependent repression incompletely resolved"]},{"year":2009,"claim":"Defined a bacterial immune-evasion mechanism by identifying FPR1 as the target of the S. aureus FLIPr-like inhibitor and mapping the inhibitor's required N-terminal phenylalanine.","evidence":"Calcium and chemotaxis assays in neutrophils, transfected cell binding, FLIPr-like N-terminal mutagenesis","pmids":["19846866"],"confidence":"High","gaps":["FLIPr-like binding site on FPR1 not mapped","In vivo relevance to S. aureus infection not tested here"]},{"year":2010,"claim":"Established FPR1 cross-talk with growth factor receptors, showing FPR1 is required for EGFR/TrkA phosphorylation and downstream ERK/ROS/MMP-9 responses in monocytes, positioning FPR1 as a signaling integrator.","evidence":"Receptor-specific inhibitors, siRNA of each receptor, phospho-immunoblots, ROS/MMP-9/CD11b readouts","pmids":["20566383"],"confidence":"Medium","gaps":["Physical basis of FPR1-EGFR/TrkA cross-talk not shown","Single cell system"]},{"year":2010,"claim":"Confirmed FPR1 as the exclusive high-affinity receptor for mitochondrial damage-associated formyl peptides in human neutrophils, cementing its role as a sensor of host tissue injury.","evidence":"Antibody blockade of FPR1 versus FPRL1 with calcium, chemotaxis, and oxidative burst readouts","pmids":["20539176"],"confidence":"High","gaps":["Did not establish in vivo contribution of mitochondrial peptides to sterile inflammation"]},{"year":2011,"claim":"Revealed a developmental/regenerative role by showing FPR1 drives osteoblastic differentiation of mesenchymal stem cells through a PLC/D-Ca2+-CaMKII-ERK-CREB pathway.","evidence":"Cyclosporin H antagonism, phospho-immunoblots, differentiation assays, zebrafish and rabbit bone formation models","pmids":["21372136"],"confidence":"High","gaps":["Endogenous osteogenic FPR1 ligand not identified","Connection to immune formyl peptide sensing unclear"]},{"year":2012,"claim":"Demonstrated in vivo pathological recruitment function, with Fpr1 ablation protecting against cigarette-smoke emphysema by preventing neutrophil/macrophage influx.","evidence":"Fpr1 knockout mouse, BAL cell counts, histology, expression profiling, cyclosporin H","pmids":["22461430"],"confidence":"High","gaps":["Driving ligand in smoke-induced inflammation not defined"]},{"year":2013,"claim":"Distinguished FPR1 from FPR2 in acute lung injury, showing FPR1 is specifically required for neutrophil infiltration across all lung compartments.","evidence":"Fpr1-/- versus Fpr2-/- mice in LPS aerosol ALI, BAL counts, histology, receptor antagonists","pmids":["23860188"],"confidence":"High","gaps":["Relevant endogenous formyl peptide ligand during LPS injury not identified"]},{"year":2014,"claim":"Established annexin A1-FPR1 as a death-signaling axis, showing FPR1 on keratinocytes transduces ANXA1 into RIP1/RIP3-dependent necroptosis in SJS/TEN, and identified FAM19A4/TAFA4 as a new FPR1 agonist promoting macrophage function.","evidence":"Mass spectrometry, anti-ANXA1 depletion, RIP1/RIP3 pathway analysis, mouse SJS/TEN model; radioligand competition, internalization, blockade, and Akt/phagocytosis assays for FAM19A4","pmids":["25031270","25109685"],"confidence":"High","gaps":["How FPR1 selects necroptotic versus chemotactic outputs unresolved","FAM19A4 binding site on FPR1 not mapped"]},{"year":2014,"claim":"Showed a physical FPR1-uPAR-integrin signaling module at the cell surface, with co-IP and co-localization linking uPAR-dependent migration to intact FPR1 interaction.","evidence":"Co-IP, confocal co-localization, uPAR siRNA, antibody blocking, migration in transfected HEK293 cells","pmids":["24466048"],"confidence":"Medium","gaps":["Single Co-IP system without reciprocal validation in primary cells","Stoichiometry of the FPR1/uPAR/integrin complex unknown"]},{"year":2016,"claim":"Generalized the tumor-promoting signaling program beyond glioblastoma, showing reciprocal gain/loss-of-function FPR1 control of neuroblastoma tumorigenesis via MAPK/ERK, PI3K/Akt, and p38 pathways.","evidence":"Calcium flux, phospho-immunoblots, cyclosporin H, shRNA and overexpression with xenografts in neuroblastoma cells","pmids":["27432059"],"confidence":"High","gaps":["Endogenous tumor ligand source not defined"]},{"year":2016,"claim":"Identified a regulatory route for receptor desensitization, showing exogenous CO promotes FPR1 internalization through p38 MAPK rather than GRK2 to suppress neutrophil recruitment.","evidence":"Migration assays, FPR1 internalization studies, p38 versus GRK2 inhibition in neutrophils","pmids":["27144520"],"confidence":"Medium","gaps":["Molecular target of CO upstream of FPR1 internalization unclear","Single lab"]},{"year":2019,"claim":"Revealed FPR1 as a pathogen-exploited entry portal and a beneficial commensal sensor, with Y. pestis LcrV binding FPR1 to enable T3SS translocation (loss-of-function protective) and gut FPR1 transducing commensal LGG signals into neuronal ROS and motility.","evidence":"LcrV-FPR1 binding, Fpr1-/- infection and survival, human FPR1R190W neutrophil assay; Fpr1-KO mouse gut model with FISH, ROS/p-MAPK1 readouts and GI motility","pmids":["31534221","30930024"],"confidence":"High","gaps":["LcrV binding site on FPR1 not structurally mapped","Commensal-derived formyl peptide ligand in gut not chemically defined"]},{"year":2020,"claim":"Demonstrated cell-intrinsic, tissue-specific recruitment roles in fibrosis and immunosurveillance, with FPR1 required for neutrophil-driven bleomycin lung fibrosis and for dendritic-cell ANXA1 sensing in anthracycline-induced immunogenic cell death.","evidence":"Fpr1-/- bleomycin model with neutrophil adoptive transfer and multi-organ comparison; Fpr1-/- tumor models, DC/T-cell assays, pIC rescue, carcinogenesis model","pmids":["32102985","33046534"],"confidence":"High","gaps":["Opposing protective (anticancer immunity) versus pathogenic (fibrosis) roles not mechanistically reconciled","Determinants of tissue specificity unknown"]},{"year":2020,"claim":"Characterized pharmacological tractability and biased signaling, with the FPR1-specific agonist RE-04-001 activating PLC-Ca2+ and ERK while minimally recruiting β-arrestin, demonstrating that FPR1 effector arms can be selectively engaged.","evidence":"Ca2+ flux, superoxide, ERK, and β-arrestin recruitment assays in FPR1/FPR2 cells and neutrophils","pmids":["33040403"],"confidence":"Medium","gaps":["Structural basis of biased agonism not defined","In vivo consequences of arrestin-sparing signaling untested"]},{"year":2022,"claim":"Linked FPR1 dysfunction to disease pathophysiology, showing high glucose impairs FPR-mediated chemotaxis to delay diabetic wound neutrophil trafficking, and FPR1 promotes post-stroke leukocyte brain infiltration and worse outcomes.","evidence":"Diabetic Lepr db/db model with in vitro glucose exposure and CCL3 rescue; focal ischemia in Fpr1-/- mice with cFLFLF antagonist and migration assays","pmids":["35112667","35547761"],"confidence":"Medium","gaps":["Molecular mechanism of glucose-induced FPR signaling impairment incompletely defined","Single labs"]},{"year":null,"claim":"How FPR1 selects between divergent functional outputs — chemotaxis, oxidase activation, necroptosis, tumor growth, and protective anticancer immunity — from the same Gi-coupled receptor remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No structural model of agonist-bound FPR1 in the corpus","Determinants of ligand-biased and tissue-specific output not established","Identity of many endogenous tumor and tissue agonists unknown"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0060089","term_label":"molecular transducer activity","supporting_discovery_ids":[0,3,17]},{"term_id":"GO:0001618","term_label":"virus receptor activity","supporting_discovery_ids":[27]}],"localization":[{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[1,24]}],"pathway":[{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[0,2,25]},{"term_id":"R-HSA-168256","term_label":"Immune System","supporting_discovery_ids":[3,17,21,29]},{"term_id":"R-HSA-1643685","term_label":"Disease","supporting_discovery_ids":[19,22,27,30]},{"term_id":"R-HSA-5357801","term_label":"Programmed Cell Death","supporting_discovery_ids":[22,29]}],"complexes":[],"partners":["ANXA1","FAM19A4","PLAUR","ITGAV","EGFR","NTRK1","LCRV"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"P21462","full_name":"N-formyl peptide receptor 1","aliases":["N-formylpeptide chemoattractant receptor","fMet-Leu-Phe receptor","fMLP receptor"],"length_aa":350,"mass_kda":38.4,"function":"Pattern recognition G-protein coupled receptor (PRR/GPCR) involved in innate recognition of N-formyl-methionyl peptides derived from invading microbes and host mitochondria as pathogen- and damage-associated molecular patterns (PAMPs and DAMPs). Functions as a sensor of PAMPs and DAMPs released upon microbial infection or tissue damage, triggering immune cell activation and chemotaxis to eliminate pathogens and restore tissue homeostasis (PubMed:24108355, PubMed:25605714, PubMed:35217703, PubMed:36064945). Peptide binding leads to conformational changes coupled to heterotrimeric G(i) protein signaling. Upon GDP to GTP conversion, G(i)-alpha subunit dissociates from G-beta and G-gamma subunits. Free G(i)-alpha subunit inhibits cyclic adenylate cyclase and cAMP synthesis whereas the G-beta and G-gamma dimer activates downstream phospholipase C-beta and phosphoinositide 3-kinase signaling cascades leading to Ca(2+) influx (PubMed:10514456, PubMed:15153520, PubMed:1712023, PubMed:25605714, PubMed:35217703, PubMed:36064945). Displays two affinity states for peptide agonists, low and high, likely accounting for selective signaling of myeloid cell functions at different phases of the inflammatory response. Subnanomolar concentrations of peptide agonists induce myeloid cell chemotaxis, whereas micromolar concentrations trigger degranulation and superoxide production (PubMed:2161213, PubMed:2176894, PubMed:24108355, PubMed:25605714). May recognize a myriad of bacterial signal peptides indicative of an evolutionary conserved detection mechanism in host defense against bacterial infection. Triggers bactericidal functions of neutrophils and phagocytes in response to N-formyl-Met-Leu-Phe (fMLF) which is part of the signal peptide sequences of hundreds distinct bacterial strains (PubMed:25605714). In the homeostatic wound healing response to tissue injury, senses 'necrotaxis' DAMP-type signals released in the form of mitochondria-derived N-formylated peptides and guides neutrophil trafficking toward necrotic cells within the injury site (By similarity). In the context of antitumor immunity, interacts with ANXA1 and guides dendritic cell positioning in close proximity to necrotic tumor cells, allowing for tumor-associated antigen uptake and cross-presentation to T cells (PubMed:24108355, PubMed:26516201). Receptor for TAFA4, mediates its effects on chemoattracting macrophages, promoting phagocytosis and increasing reactive oxygen species (ROS) release (PubMed:25109685). Receptor for cathepsin CTSG, leading to increased phagocyte chemotaxis (PubMed:15210802). Beyond canonical N-terminal formylated peptide agonists, can also be activated by C-terminal amidated peptides, which appear to all share a tripartite structure motif oriented around a carboxyl group (PubMed:24108355, PubMed:25605714). Differential signaling is also defined by receptor oligomerization state. Pro-resolving ligands, such as lipoxin A4 or ANXA1, induce the formation of FPR1:FPR2 heterodimers triggering proapoptotic JNK pathway in neutrophils (PubMed:24108355) (Microbial infection) Used by Y. pestis as a receptor on human immune cells. Upon infection, Y. pestis releases N-formyl peptides that activate FPR1-mediated immune signaling and chemotaxis. This leads to Y. pestis docking on FPR1 via the lcrV needle cap protein of its type III secretion system (T3SS) followed by the delivery of effector proteins into host immune cells, ultimately triggering immune cell apoptosis","subcellular_location":"Cell membrane","url":"https://www.uniprot.org/uniprotkb/P21462/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/FPR1","classification":"Not Classified","n_dependent_lines":0,"n_total_lines":1208,"dependency_fraction":0.0},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/FPR1","total_profiled":1310},"omim":[{"mim_id":"605246","title":"COMPLEMENT COMPONENT 3a RECEPTOR 1; C3AR1","url":"https://www.omim.org/entry/605246"},{"mim_id":"605086","title":"TRIGGERING RECEPTOR EXPRESSED ON MYELOID CELLS 2; TREM2","url":"https://www.omim.org/entry/605086"},{"mim_id":"605085","title":"TRIGGERING RECEPTOR EXPRESSED ON MYELOID CELLS 1; TREM1","url":"https://www.omim.org/entry/605085"},{"mim_id":"603195","title":"G PROTEIN-COUPLED RECEPTOR 32; GPR32","url":"https://www.omim.org/entry/603195"},{"mim_id":"602351","title":"CHEMERIN CHEMOKINE-LIKE RECEPTOR 1; CMKLR1","url":"https://www.omim.org/entry/602351"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Golgi apparatus","reliability":"Approved"},{"location":"Nucleoplasm","reliability":"Additional"},{"location":"Nucleoli","reliability":"Additional"}],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in many","driving_tissues":[{"tissue":"bone marrow","ntpm":179.3},{"tissue":"lymphoid tissue","ntpm":175.1}],"url":"https://www.proteinatlas.org/search/FPR1"},"hgnc":{"alias_symbol":["FPR","FMLP"],"prev_symbol":[]},"alphafold":{"accession":"P21462","domains":[{"cath_id":"1.20.1070.10","chopping":"28-315","consensus_level":"high","plddt":89.9059,"start":28,"end":315}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/P21462","model_url":"https://alphafold.ebi.ac.uk/files/AF-P21462-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-P21462-F1-predicted_aligned_error_v6.png","plddt_mean":83.81},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=FPR1","jax_strain_url":"https://www.jax.org/strain/search?query=FPR1"},"sequence":{"accession":"P21462","fasta_url":"https://rest.uniprot.org/uniprotkb/P21462.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/P21462/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/P21462"}},"corpus_meta":[{"pmid":"19498085","id":"PMC_19498085","title":"International Union of Basic and Clinical Pharmacology. 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Molecular characterization of FPR2, a second mouse neutrophil FPR.","date":"1999","source":"The Journal of experimental medicine","url":"https://pubmed.ncbi.nlm.nih.gov/10477558","citation_count":95,"is_preprint":false},{"pmid":"19741154","id":"PMC_19741154","title":"Ficolin-1 is present in a highly mobilizable subset of human neutrophil granules and associates with the cell surface after stimulation with fMLP.","date":"2009","source":"Journal of leukocyte biology","url":"https://pubmed.ncbi.nlm.nih.gov/19741154","citation_count":92,"is_preprint":false},{"pmid":"32102985","id":"PMC_32102985","title":"FPR-1 is an important regulator of neutrophil recruitment and a tissue-specific driver of pulmonary fibrosis.","date":"2020","source":"JCI insight","url":"https://pubmed.ncbi.nlm.nih.gov/32102985","citation_count":89,"is_preprint":false},{"pmid":"30930024","id":"PMC_30930024","title":"Interactions Between Commensal Bacteria and Enteric Neurons, via FPR1 Induction of ROS, Increase 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electropermeabilized neutrophils, pertussis toxin inhibition, dibutyryl cAMP inhibition studies\",\n      \"journal\": \"The Journal of Clinical Investigation\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods (kinase assay, GTP-loading, pertussis toxin, PKC inhibitors) in a focused mechanistic study replicated across signaling nodes\",\n      \"pmids\": [\"8040337\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1994,\n      \"finding\": \"The NH2-terminal extracellular region of FPR is NOT required for plasma membrane trafficking or high-affinity N-formylpeptide binding (in contrast to C5aR); replacing FPR's NH2-terminus with C5aR sequence still permitted normal surface expression and ligand binding.\",\n      \"method\": \"Chimeric receptor mutagenesis, cell surface expression assays, radioligand binding assays\",\n      \"journal\": \"The Journal of Biological Chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — reconstitution with chimeric mutagenesis and direct binding assays; clear positive and negative controls\",\n      \"pmids\": [\"8106386\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"FMLP-stimulated FPR1 activation in human neutrophils requires p38 MAP kinase for chemotaxis and superoxide generation; pharmacological inhibition of p38 (SB20358) markedly suppressed both responses, whereas p44/42 MAP kinase inhibition (PD98059) did not.\",\n      \"method\": \"Kinase phosphorylation analysis, selective kinase inhibitors (SB20358, PD98059), superoxide generation assay, chemotaxis assay in human neutrophils\",\n      \"journal\": \"Journal of Immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — pharmacological dissection with selective inhibitors across multiple functional readouts in primary human cells\",\n      \"pmids\": [\"9469462\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"Mouse FPR1 and a second lower-affinity receptor (FPR2) together account for the biphasic fMLF concentration-chemotaxis curve in mouse neutrophils; FPR knockout neutrophils lose the high-sensitivity optimum, establishing that FPR1 mediates responses to low concentrations of N-formylpeptide.\",\n      \"method\": \"Calcium flux and chemotaxis assays in HEK293 cells transfected with FPR or FPR2, comparison of wild-type versus FPR-knockout mouse neutrophils\",\n      \"journal\": \"The Journal of Experimental Medicine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic knockout combined with transfected cell reconstitution and functional dose-response analysis\",\n      \"pmids\": [\"10477558\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"Amyloid-β42 acts as a chemotactic agonist at FPRL1 (FPR2/ALX), not FPR1; FPR1-expressing cells do not respond, establishing receptor selectivity for this ligand.\",\n      \"method\": \"Chemotaxis assays in HL-60 cells stably expressing FPR1 or FPRL1; receptor-specific functional readouts\",\n      \"journal\": \"The Journal of Neuroscience\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — transfected cell lines with functional chemotaxis readout, single lab study\",\n      \"pmids\": [\"11160457\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"FPR1 mediates fMLF-induced NADPH oxidase-dependent superoxide production in mouse neutrophils; FPR1-deficient neutrophils show markedly reduced superoxide at low fMLF concentrations, but a second Gi-coupled receptor (likely FPR2) maintains oxidase activation at high concentrations.\",\n      \"method\": \"Superoxide production assay comparing FPR+/+ and FPR−/− mouse neutrophils; pharmacological inhibition with pertussis toxin\",\n      \"journal\": \"Cellular Immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic knockout model with clear dose-response comparison and pharmacological confirmation of Gi coupling\",\n      \"pmids\": [\"12470609\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"Annexin A1 (AnxA1) and its mimetic peptide Ac2-26 exert anti-adhesive effects on leukocytes partly through FPR1 and partly through ALXR (FPR2); in FPR-deficient mice, Ac2-26 retains ~50% inhibitory activity blocked by the pan-FPR antagonist Boc2, and FPR-deficient neutrophils express functional ALXR.\",\n      \"method\": \"In vivo ischemia/reperfusion intravital microscopy in FPR-knockout mice; in vitro neutrophil activation at high fMLP concentrations; RT-PCR and protein detection for ALXR\",\n      \"journal\": \"Blood\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic KO mouse model combined with in vivo intravital readout and in vitro pharmacological validation\",\n      \"pmids\": [\"12560218\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"Listeria monocytogenes-derived N-formylpeptides preferentially activate FPR1 (~100-fold more potent than FPRL1), whereas human mitochondria-derived N-formylpeptides (fMLKLIV, fMMYALF, fMFADRW) are equally potent agonists of both FPR1 and FPRL1, with EC50 values in the 10–160 nM range.\",\n      \"method\": \"Intracellular calcium mobilization (Fura-2) in HL-60 cell lines stably expressing FPR1, FPRL1, or FPRL2; chemotaxis assays\",\n      \"journal\": \"European Journal of Immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — receptor-expressing stable cell lines, quantitative dose-response across multiple peptides and receptors\",\n      \"pmids\": [\"16025565\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"The uPAR-derived SRSRY peptide activates FPR1 to induce cell migration, F-actin polarization, and cross-talk with the vitronectin receptor αvβ5; fMLP competition experiments and FPR1 pathway dependence established FPR1 as the transducing receptor for SRSRY-stimulated cytoskeletal rearrangement.\",\n      \"method\": \"Competitive ligand binding, migration assays on vitronectin-coated filters, F-actin immunostaining, PKC activity and ERK1/2 phosphorylation, αvβ5 co-immunoprecipitation\",\n      \"journal\": \"The Journal of Biological Chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple signaling readouts and competitive displacement, single lab\",\n      \"pmids\": [\"15866865\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"Formylpeptide receptor FPR1 mediates chemotaxis, proliferation, and VEGF production in human glioblastoma cells (U-87); FPR1 siRNA knockdown substantially reduced xenograft tumor volume, and necrotic glioblastoma cells release endogenous FPR1 agonist(s).\",\n      \"method\": \"RT-PCR, chemotaxis assay, siRNA knockdown, xenograft nude mouse model, VEGF ELISA, basophil leukemia cell FPR activation assay\",\n      \"journal\": \"Journal of the National Cancer Institute\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — loss-of-function siRNA with xenograft phenotype plus multiple functional readouts (chemotaxis, proliferation, VEGF) in same study\",\n      \"pmids\": [\"15928303\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"An annexin AI peptide (Ac9-25) activates neutrophil NADPH oxidase through FPR1 (not FPRL1); the inhibitory signal generated by the same peptide on oxidase activity is transduced by a separate, unidentified receptor distinct from FPR1 and FPRL1.\",\n      \"method\": \"Receptor antagonists/inhibitors, receptor desensitization experiments, FPR1/FPRL1-transfected cell lines, superoxide anion release assay\",\n      \"journal\": \"Journal of Leukocyte Biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — transfected cell reconstitution plus pharmacological dissection with multiple antagonists identifying two distinct signaling arms\",\n      \"pmids\": [\"15951351\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"FPR1 activation by fMLF in glioblastoma cells (U87) drives production of both VEGF and IL-8 (CXCL8); FPR1 siRNA abolished production of both angiogenic factors and reduced tumor angiogenesis in vivo.\",\n      \"method\": \"FPR1 siRNA transfection, fMLF stimulation, RT-PCR and ELISA for VEGF and IL-8, nude mouse xenograft angiogenesis assessment\",\n      \"journal\": \"Journal of Neuro-oncology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — siRNA loss-of-function with multiple angiogenic factor readouts and in vivo confirmation, single lab\",\n      \"pmids\": [\"17611713\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"FPR1 expressed on glioblastoma stem cells (CD133+ GSCs from U87) mediates calcium flux and VEGF production in response to fMLF stimulation.\",\n      \"method\": \"Flow cytometry for CD133, calcium flux assay, VEGF measurement, xenograft tumor formation\",\n      \"journal\": \"The Journal of Pathology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — functional receptor assays (calcium flux) in sorted stem cell subpopulation, single lab\",\n      \"pmids\": [\"18523971\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"p53 binds to the FPR1 promoter region and suppresses FPR1 expression in glioblastoma cells; DNA methyltransferase inhibition (5-Aza-2'-deoxycytidine) promotes glioblastoma differentiation and reduces FPR1 expression via a p53-dependent mechanism.\",\n      \"method\": \"Chromatin immunoprecipitation (ChIP) for p53 binding to FPR1 promoter, methylation-specific PCR, p53 overexpression, flow cytometry, nude mouse xenograft\",\n      \"journal\": \"Carcinogenesis\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — ChIP demonstrates direct p53-FPR1 promoter binding; supported by overexpression experiments, single lab\",\n      \"pmids\": [\"19037090\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"FPR1 is identified as the receptor for the Staphylococcus aureus protein FLIPr-like, which inhibits FPR1-mediated neutrophil calcium mobilization and chemotaxis; the second N-terminal phenylalanine of FLIPr-like is required specifically for FPR1 inhibition.\",\n      \"method\": \"Neutrophil calcium mobilization assay, chemotaxis assay, transfected cell binding studies, mutagenesis of FLIPr-like N-terminal residues\",\n      \"journal\": \"Journal of Immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — mutagenesis of inhibitor combined with receptor-transfected cell assays and functional neutrophil readouts\",\n      \"pmids\": [\"19846866\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"FPR1 expression confers increased motility and invasive tumor phenotype to glioblastoma cells; FPR1-overexpressing clones formed more rapidly growing and invasive xenograft tumors, and serum-derived FPR1 agonist activity stimulated FPR1-dependent cell motility.\",\n      \"method\": \"Single-cell cloning, flow cytometry, RT-PCR, wound-healing motility assay, calcium flux, nude mouse xenograft with subcutaneous implantation\",\n      \"journal\": \"British Journal of Cancer\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — gain-of-function overexpression plus isogenic clonal comparison with in vivo confirmation, single lab\",\n      \"pmids\": [\"20197768\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"FPR1 cross-talks with EGFR and TrkA in monocytes: FPR1 inhibition (cyclosporin H) prevents EGFR and TrkA phosphorylation by their own ligands, and FPR1 siRNA suppresses EGF- and NGF-mediated ERK phosphorylation, ROS production, MMP-9 production, and CD11b upregulation.\",\n      \"method\": \"Receptor-specific inhibitors, siRNA knockdown of each receptor, immunoblotting for receptor phosphorylation and ERK, ROS and MMP-9 measurements, CD11b expression by flow cytometry\",\n      \"journal\": \"Cellular Signalling\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — siRNA knockdown plus pharmacological inhibitors with multiple functional readouts, single lab\",\n      \"pmids\": [\"20566383\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"Mitochondrial degradation products (formylated mitochondrial peptides) activate human neutrophils exclusively through FPR1 (high-affinity receptor); anti-FPR1 antibody completely blocked calcium responses, whereas anti-FPRL1 antibody did not.\",\n      \"method\": \"Cytosolic calcium ([Ca]i) assay with antibody blockade of FPR1 and FPRL1, chemotaxis in trans-wells, oxidative burst assay\",\n      \"journal\": \"The Journal of Trauma\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — antibody-mediated receptor blockade with complete inhibition, multiple functional readouts (Ca2+ flux, chemotaxis, oxidative burst)\",\n      \"pmids\": [\"20539176\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"FPR1 mediates fMLP-induced osteoblastic differentiation of human bone marrow mesenchymal stem cells via a phospholipase C/D–Ca2+–CaMKII–ERK–CREB signaling pathway; FPR1 expression is specifically upregulated during osteogenesis, and the FPR1-selective antagonist cyclosporin H blocks fMLP-stimulated osteogenesis.\",\n      \"method\": \"qPCR, flow cytometry, cyclosporin H antagonism, phospho-specific immunoblotting, osteogenic/adipogenic differentiation assays, zebrafish and rabbit in vivo bone formation models\",\n      \"journal\": \"The Journal of Biological Chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — pharmacological antagonist blocks pathway with multiple orthogonal signaling readouts and in vivo models\",\n      \"pmids\": [\"21372136\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"Genetic ablation of Fpr1 in mice protects against cigarette smoke-induced lung emphysema by preventing neutrophil and macrophage recruitment to the lung; the FPR1 antagonist cyclosporin H similarly attenuated acute inflammatory responses.\",\n      \"method\": \"Fpr1 knockout mouse model, histological assessment, inflammatory cell counts in BAL, gene expression profiling, pharmacological antagonism with cyclosporin H\",\n      \"journal\": \"American Journal of Respiratory Cell and Molecular Biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic KO with pharmacological confirmation and histological/cellular phenotype quantification\",\n      \"pmids\": [\"22461430\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"FPR1 activation by annexin A1 (ANXA1) transactivates EGFR in glioblastoma cells to promote chemotaxis, invasion, growth, and angiogenic factor production.\",\n      \"method\": \"Cited in review context (PMID 22863814); mechanistic support from referenced experimental work showing FPR1-EGFR transactivation\",\n      \"journal\": \"International Immunopharmacology\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 4 / Weak — described in a review abstract without primary experimental detail presented in this abstract\",\n      \"pmids\": [\"22863814\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"In acute lung injury (ALI) induced by aerosolized LPS, FPR1 (but not FPR2) is required for neutrophil infiltration into all lung compartments; Fpr1-/- mice and pharmacological FPR1 blockade reduced alveolar, interstitial, and intravascular neutrophil counts and attenuated lung edema.\",\n      \"method\": \"Fpr1-/- and Fpr2-/- mouse comparison, LPS aerosol ALI model, BAL cell counts, histology, specific receptor antagonists\",\n      \"journal\": \"Journal of Innate Immunity\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic KO with pharmacological confirmation across multiple lung compartments\",\n      \"pmids\": [\"23860188\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"FPR1 is the receptor for annexin A1 on SJS/TEN keratinocytes; annexin A1 secreted by drug-stimulated PBMCs binds FPR1 (overexpressed in SJS/TEN keratinocytes) to induce necroptosis via RIP1/RIP3 complex formation.\",\n      \"method\": \"Mass spectrometry identification of annexin A1, anti-annexin A1 antibody depletion, FPR1 expression by immunostaining, RIP1/RIP3 pathway analysis, mouse SJS/TEN model with necroptosis inhibitor\",\n      \"journal\": \"Science Translational Medicine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods (MS, antibody depletion, pathway genetic dissection, mouse model) establishing AnxA1-FPR1-necroptosis axis\",\n      \"pmids\": [\"25031270\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"FAM19A4 (TAFA4) is a novel agonist ligand of FPR1; binding established by receptor internalization assays, radioligand competition binding, and receptor blockade; FAM19A4/FPR1 signaling promotes macrophage migration, phagocytosis, and Akt phosphorylation.\",\n      \"method\": \"Receptor internalization assay, radioligand binding assay, receptor blockade, macrophage chemotaxis, phagocytosis assay, Akt phosphorylation by immunoblot\",\n      \"journal\": \"Cellular & Molecular Immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — three independent binding methods (internalization, radioligand competition, blockade) plus functional downstream signaling readouts\",\n      \"pmids\": [\"25109685\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"uPAR co-localizes and co-immunoprecipitates with FPR1 at the cell surface; uPAR expression drives FPR1/β1-integrin co-localization that is further enhanced by the FPR1 ligand WKYMVm, and uPAR-dependent cell migration requires intact uPAR–FPR1 interaction.\",\n      \"method\": \"Co-immunoprecipitation, confocal co-localization, siRNA knockdown of uPAR, antibody blocking, migration assays in uPAR-transfected HEK293 cells\",\n      \"journal\": \"PLoS ONE\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-IP and siRNA with functional migration readout, single lab\",\n      \"pmids\": [\"24466048\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"FPR1 activation by fMLP in neuroblastoma cells induces intracellular calcium mobilization and activates MAPK/Erk, PI3K/Akt, and p38-MAPK pathways; FPR1 shRNA knockdown delays xenograft tumor development, while FPR1 overexpression promotes augmented tumorigenesis.\",\n      \"method\": \"Calcium mobilization assay, phospho-specific immunoblotting, cyclosporin H antagonism, shRNA knockdown and FPR1 cDNA overexpression with nude mouse xenograft\",\n      \"journal\": \"BMC Cancer\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal gain/loss-of-function with xenograft phenotype and pharmacological validation of signaling pathways\",\n      \"pmids\": [\"27432059\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"Exogenous CO (CORM-2) inhibits FPR1-mediated neutrophil infiltration by promoting FPR1 internalization through inhibition of p38 MAPK, but not through GRK2.\",\n      \"method\": \"Affymetrix gene chip analysis, under-agarose migration assay, FPR1 internalization studies, p38 MAPK inhibition vs. GRK2 inhibition comparisons\",\n      \"journal\": \"Oncotarget\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — mechanistic dissection of FPR1 internalization via p38 vs. GRK2 with functional migration readout, single lab\",\n      \"pmids\": [\"27144520\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"FPR1 is the direct receptor on immune cells exploited by Yersinia pestis for type III secretion system effector translocation; the Y. pestis needle cap protein LcrV binds FPR1, and Fpr1-deficient mice show increased survival; the FPR1R190W allele in humans protects neutrophils from Y. pestis destruction.\",\n      \"method\": \"Direct binding of LcrV to FPR1, Fpr1-/- mouse infection model (survival, antibody responses), ex vivo neutrophil translocation assay with FPR1R190W variant cells\",\n      \"journal\": \"Nature\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — direct protein binding plus genetic KO infection model plus human variant functional assay across multiple orthogonal approaches\",\n      \"pmids\": [\"31534221\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"FPR1 in the gut mediates commensal bacterium (LGG)-induced ROS production and MAPK1 phosphorylation in myenteric neurons; FPR1-knockout mice fail to show LGG-induced ROS production, ChAT upregulation, or increased GI motility.\",\n      \"method\": \"FPR1-KO mouse model, fluorescence in situ hybridization for FPR1 in myenteric plexi, immunostaining/immunoblots for ROS and p-MAPK1, GI transit/motility measurements, LGG gavage\",\n      \"journal\": \"Gastroenterology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic KO with multiple orthogonal readouts (molecular, cellular, physiological) and bacterial adhesion-mutant controls\",\n      \"pmids\": [\"30930024\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"FPR1 on dendritic cells is required for ANXA1-mediated immunogenic cell death signaling after anthracycline chemotherapy; tumors lacking ANXA1 or growing in Fpr1-/- mice show deficient DC- and T-lymphocyte-mediated anticancer immunity, and FPR1 loss-of-function is associated with earlier breast cancer onset.\",\n      \"method\": \"Fpr1-/- mouse tumor models, DC/T-cell functional assays, pIC (TLR3 ligand) rescue experiments, carcinogen-induced tumor model in Fpr1-/- mice\",\n      \"journal\": \"Cancer Discovery\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic KO model with multiple immune cell functional assays, pharmacological rescue (pIC), and carcinogenesis model\",\n      \"pmids\": [\"33046534\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"FPR1 deficiency (fpr1-/-) protects mice from bleomycin-induced pulmonary fibrosis by preventing neutrophil recruitment to the lung; adoptive transfer established that the neutrophil recruitment defect is intrinsic to fpr1-/- neutrophils. FPR1 deficiency did not affect renal or hepatic fibrosis, demonstrating tissue-specific function.\",\n      \"method\": \"Fpr1-/- mouse bleomycin model, neutrophil adoptive transfer, histology, cell counts, gene expression analysis\",\n      \"journal\": \"JCI Insight\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic KO with adoptive transfer establishing cell-intrinsic mechanism, tissue specificity confirmed across three organ models\",\n      \"pmids\": [\"32102985\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"FPR1 modulates NLRP3 inflammasome signaling and NF-κB nuclear translocation in bronchiolitis obliterans syndrome; Fpr1 KO mice show greater reduction in NF-κB, NLRP3, and MAPK pathway activation than IL-1β/IL-18 or Casp-1 KO mice.\",\n      \"method\": \"Transgenic KO mouse model of allogeneic heterotopic tracheal transplantation BOS, molecular pathway analysis (NF-κB, NLRP3, MAPK), TUNEL apoptosis assay, immunohistochemistry\",\n      \"journal\": \"International Journal of Molecular Sciences\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic KO with pathway analysis; comparative KO design is informative but mechanistic link is correlative\",\n      \"pmids\": [\"32244997\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"High glucose conditions impair FPR-mediated chemotaxis signaling in diabetic neutrophils, delaying neutrophil trafficking in wounds of Lepr(db/db) type 2 diabetic mice; auxiliary CCL3 receptor engagement overrides the FPR signaling impairment.\",\n      \"method\": \"Diabetic mouse model (Lepr db/db), in vitro glucose exposure of neutrophils, chemotaxis assays, in vivo neutrophil wound trafficking measurement, CCL3 rescue experiment\",\n      \"journal\": \"eLife\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — diabetic mouse model with in vitro mechanistic confirmation and functional rescue, single lab\",\n      \"pmids\": [\"35112667\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"FPR1 facilitates splenocyte migration into ischemic brain tissue and promotes proinflammatory cytokine production after stroke; Fpr1-/- mice showed reduced peripheral monocyte/neutrophil infiltration into ischemic brain and improved neurological outcomes.\",\n      \"method\": \"Transient focal brain ischemia in Fpr1-/- mice, splenocyte migration assays in vivo and in vitro, cFLFLF FPR1 antagonist treatment, cytokine measurements, neurological scoring\",\n      \"journal\": \"Theranostics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic KO combined with pharmacological antagonism and functional migration assays, single lab\",\n      \"pmids\": [\"35547761\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"FPR1 pepducins (lipidated peptides based on the third intracellular loop of FPR1) do not activate FPR1 but instead potently inhibit FPR2-mediated neutrophil superoxide production and granule mobilization; the FPR2-specific K231 residue (vs. FPR1's Q231) determines pepducin activity.\",\n      \"method\": \"Pepducin receptor selectivity assay in FPR1/FPR2-transfected cells and human neutrophils, amino acid substitution studies of third intracellular loop, superoxide production and granule mobilization assays\",\n      \"journal\": \"Biochimica et Biophysica Acta\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — mutagenesis of specific residues plus transfected cell reconstitution, single lab; finding is primarily about FPR2 with FPR1 as negative control\",\n      \"pmids\": [\"23562731\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"The small compound RE-04-001 is a highly potent FPR1-specific agonist (EC50 ~1 nM for NADPH oxidase activation) that displays biased signaling: strongly activates PLC-PIP2-Ca2+ and ERK1/2 pathways but shows minimal β-arrestin recruitment compared to fMLF.\",\n      \"method\": \"FPR1/FPR2 receptor-expressing cells and human neutrophils, Ca2+ flux assay, superoxide production, ERK phosphorylation, β-arrestin recruitment assay, chemotaxis assay, receptor-selective antagonist confirmation\",\n      \"journal\": \"Journal of Leukocyte Biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple signaling pathway readouts with biased agonism characterization, single lab\",\n      \"pmids\": [\"33040403\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"FPR1 is a seven-transmembrane Gi-coupled G protein-coupled receptor on phagocytic leukocytes (and some other cell types) that binds N-formylated bacterial and mitochondrial peptides (including fMLF), as well as endogenous ligands such as annexin A1 (ANXA1), FAM19A4/TAFA4, and the Y. pestis needle-cap protein LcrV, to activate Gi2-Ras-Raf-MEK-MAPK signaling, PLC-Ca2+ mobilization, p38-MAPK, and PI3K-Akt cascades, driving neutrophil chemotaxis, NADPH oxidase-dependent superoxide production, degranulation, cytokine/VEGF/IL-8 production, and—in certain cancer and stem cell contexts—FPR1-EGFR transactivation; FPR1 also acts as a pattern-recognition receptor facilitating innate immune cell recruitment to sites of infection, tissue damage, and fibrosis, with loss-of-function conferring protection from pulmonary fibrosis, emphysema, and plague infection.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"FPR1 is a seven-transmembrane, pertussis-toxin-sensitive Gi2-coupled G-protein-coupled receptor on neutrophils and other leukocytes that detects N-formylated peptides of bacterial and mitochondrial origin and converts that recognition into chemotaxis and antimicrobial effector function [#0, #3, #17]. Ligand engagement by fMLF activates a Gi2-Ras-Raf-1-MEK-MAPK cascade, with parallel requirement for p38 MAP kinase, to drive both directional migration and NADPH oxidase-dependent superoxide production [#0, #2, #5]. FPR1 is the high-affinity receptor that confers neutrophil responses to low concentrations of N-formylpeptide, including peptides derived from Listeria and from human mitochondria, while a lower-affinity receptor (FPR2) handles high-concentration responses [#3, #7, #17]. The receptor recognizes a broad ligand repertoire beyond formyl peptides: the anti-inflammatory protein annexin A1 and its peptides act through FPR1 to modulate leukocyte adhesion and, in keratinocytes, to drive RIP1/RIP3-dependent necroptosis [#6, #22]; FAM19A4/TAFA4 is an agonist that promotes macrophage migration, phagocytosis, and Akt phosphorylation [#23]; and the uPAR-derived SRSRY peptide engages FPR1 to coordinate cytoskeletal rearrangement and integrin cross-talk [#8, #24]. Mechanistically the receptor is exploited by pathogens — the Staphylococcus aureus protein FLIPr-like antagonizes FPR1, and the Yersinia pestis needle-cap protein LcrV binds FPR1 to enable type III secretion, with loss-of-function variants protecting against plague [#14, #27]. Through its role in recruiting innate immune cells, FPR1 drives neutrophil/macrophage influx underlying cigarette-smoke emphysema, LPS acute lung injury, bleomycin pulmonary fibrosis, and post-ischemic brain inflammation, such that genetic ablation is protective in these settings [#19, #21, #30, #33]. In tumor and stem-cell contexts FPR1 promotes glioblastoma and neuroblastoma motility, proliferation, and VEGF/IL-8 production and supports anthracycline-induced immunogenic cell death via dendritic-cell ANXA1 sensing [#9, #25, #29].\",\n  \"teleology\": [\n    {\n      \"year\": 1994,\n      \"claim\": \"Established the proximal signaling logic of FPR1 by showing that formyl peptide binding couples through Gi2 to the Ras-Raf-MEK-MAPK module independent of PKC, defining how an immune chemoattractant receptor engages a canonical mitogenic cascade.\",\n      \"evidence\": \"Raf-1 kinase immunoprecipitation, Ras GTP-loading, pertussis toxin and PKC-inhibitor dissection in human neutrophils\",\n      \"pmids\": [\"8040337\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not map which intracellular receptor regions couple to Gi2\", \"Downstream functional consequences (chemotaxis vs. oxidase) not separated at this stage\"]\n    },\n    {\n      \"year\": 1994,\n      \"claim\": \"Defined receptor architecture by showing the extracellular N-terminus is dispensable for surface trafficking and high-affinity ligand binding, distinguishing FPR1's binding determinants from the related C5a receptor.\",\n      \"evidence\": \"Chimeric FPR/C5aR receptor mutagenesis with surface expression and radioligand binding assays\",\n      \"pmids\": [\"8106386\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not identify the actual transmembrane/loop residues forming the ligand pocket\", \"No structural model of the bound peptide\"]\n    },\n    {\n      \"year\": 1998,\n      \"claim\": \"Showed that distinct MAPK arms serve distinct effector outputs, with p38 (not p44/42) required for both chemotaxis and superoxide generation, refining which kinase branch drives FPR1 functional responses.\",\n      \"evidence\": \"Selective kinase inhibitors (SB20358, PD98059) with chemotaxis and superoxide readouts in human neutrophils\",\n      \"pmids\": [\"9469462\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not resolve how Gi2-Ras output integrates with p38 activation\", \"Upstream p38 activators downstream of FPR1 unidentified\"]\n    },\n    {\n      \"year\": 1999,\n      \"claim\": \"Genetic knockout established FPR1 as the high-sensitivity formyl peptide receptor responsible for the low-concentration optimum of neutrophil chemotaxis, with FPR2 covering high-concentration responses.\",\n      \"evidence\": \"Calcium flux and chemotaxis in transfected HEK293 cells and FPR-knockout versus wild-type mouse neutrophils\",\n      \"pmids\": [\"10477558\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not define the structural basis of the affinity difference between FPR1 and FPR2\", \"Biphasic response mechanism only inferred functionally\"]\n    },\n    {\n      \"year\": 2002,\n      \"claim\": \"Confirmed via knockout that FPR1 transduces fMLF-induced NADPH oxidase activation at low ligand concentrations, linking the high-affinity receptor specifically to respiratory burst.\",\n      \"evidence\": \"Superoxide assays in FPR+/+ versus FPR-/- mouse neutrophils with pertussis toxin\",\n      \"pmids\": [\"12470609\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not identify the assembly steps connecting FPR1 to the oxidase complex\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Expanded the ligand repertoire and defined receptor selectivity, showing FPR1 strongly prefers bacterial Listeria formyl peptides while mitochondrial formyl peptides activate both FPR1 and FPR2, framing FPR1 as a sensor of both microbial and host-damage signals.\",\n      \"evidence\": \"Calcium mobilization and chemotaxis in HL-60 lines stably expressing FPR1, FPRL1, or FPRL2 across multiple peptides\",\n      \"pmids\": [\"16025565\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not test these peptides in primary cells or in vivo\", \"Physiological source/concentration of mitochondrial peptides not established\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Showed FPR1 mediates non-formyl ligand signaling, including the annexin A1 peptide-driven oxidase activation and the uPAR SRSRY peptide-driven cytoskeletal/integrin cross-talk, broadening the receptor's role beyond pathogen sensing.\",\n      \"evidence\": \"Receptor-transfected cell lines, antagonist/desensitization studies, superoxide assays, migration on vitronectin, F-actin imaging and \\u03b1v\\u03b25 co-IP\",\n      \"pmids\": [\"15951351\", \"15866865\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Distinct inhibitory annexin A1 receptor remained unidentified\", \"Direct binding of SRSRY to FPR1 inferred from competition, not co-crystal\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Identified a pathogenic role for FPR1 in cancer, showing it drives glioblastoma chemotaxis, proliferation, and VEGF production and that tumor cells release endogenous FPR1 agonists, establishing autocrine/necrotic-ligand signaling in tumors.\",\n      \"evidence\": \"siRNA knockdown, xenograft tumor model, VEGF ELISA, chemotaxis and necrotic-cell agonist assays in U-87 cells\",\n      \"pmids\": [\"15928303\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Endogenous tumor-derived FPR1 agonist not chemically identified\", \"Whether effects are cell-intrinsic versus stroma-mediated not resolved\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Extended tumor signaling to angiogenesis by showing FPR1 controls both VEGF and IL-8 output to promote glioblastoma vascularization.\",\n      \"evidence\": \"FPR1 siRNA, fMLF stimulation, VEGF/IL-8 RT-PCR and ELISA, xenograft angiogenesis assessment\",\n      \"pmids\": [\"17611713\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single tumor model (U87)\", \"Signaling intermediates linking FPR1 to angiogenic transcription not defined\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Linked FPR1 expression control to tumor suppressor regulation, showing p53 directly binds the FPR1 promoter to repress expression in glioblastoma.\",\n      \"evidence\": \"ChIP for p53 at the FPR1 promoter, methylation-specific PCR, p53 overexpression, xenograft\",\n      \"pmids\": [\"19037090\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single lab/cell context\", \"Mechanism connecting DNA methylation to p53-dependent repression incompletely resolved\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Defined a bacterial immune-evasion mechanism by identifying FPR1 as the target of the S. aureus FLIPr-like inhibitor and mapping the inhibitor's required N-terminal phenylalanine.\",\n      \"evidence\": \"Calcium and chemotaxis assays in neutrophils, transfected cell binding, FLIPr-like N-terminal mutagenesis\",\n      \"pmids\": [\"19846866\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"FLIPr-like binding site on FPR1 not mapped\", \"In vivo relevance to S. aureus infection not tested here\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Established FPR1 cross-talk with growth factor receptors, showing FPR1 is required for EGFR/TrkA phosphorylation and downstream ERK/ROS/MMP-9 responses in monocytes, positioning FPR1 as a signaling integrator.\",\n      \"evidence\": \"Receptor-specific inhibitors, siRNA of each receptor, phospho-immunoblots, ROS/MMP-9/CD11b readouts\",\n      \"pmids\": [\"20566383\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Physical basis of FPR1-EGFR/TrkA cross-talk not shown\", \"Single cell system\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Confirmed FPR1 as the exclusive high-affinity receptor for mitochondrial damage-associated formyl peptides in human neutrophils, cementing its role as a sensor of host tissue injury.\",\n      \"evidence\": \"Antibody blockade of FPR1 versus FPRL1 with calcium, chemotaxis, and oxidative burst readouts\",\n      \"pmids\": [\"20539176\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not establish in vivo contribution of mitochondrial peptides to sterile inflammation\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Revealed a developmental/regenerative role by showing FPR1 drives osteoblastic differentiation of mesenchymal stem cells through a PLC/D-Ca2+-CaMKII-ERK-CREB pathway.\",\n      \"evidence\": \"Cyclosporin H antagonism, phospho-immunoblots, differentiation assays, zebrafish and rabbit bone formation models\",\n      \"pmids\": [\"21372136\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Endogenous osteogenic FPR1 ligand not identified\", \"Connection to immune formyl peptide sensing unclear\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Demonstrated in vivo pathological recruitment function, with Fpr1 ablation protecting against cigarette-smoke emphysema by preventing neutrophil/macrophage influx.\",\n      \"evidence\": \"Fpr1 knockout mouse, BAL cell counts, histology, expression profiling, cyclosporin H\",\n      \"pmids\": [\"22461430\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Driving ligand in smoke-induced inflammation not defined\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Distinguished FPR1 from FPR2 in acute lung injury, showing FPR1 is specifically required for neutrophil infiltration across all lung compartments.\",\n      \"evidence\": \"Fpr1-/- versus Fpr2-/- mice in LPS aerosol ALI, BAL counts, histology, receptor antagonists\",\n      \"pmids\": [\"23860188\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Relevant endogenous formyl peptide ligand during LPS injury not identified\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Established annexin A1-FPR1 as a death-signaling axis, showing FPR1 on keratinocytes transduces ANXA1 into RIP1/RIP3-dependent necroptosis in SJS/TEN, and identified FAM19A4/TAFA4 as a new FPR1 agonist promoting macrophage function.\",\n      \"evidence\": \"Mass spectrometry, anti-ANXA1 depletion, RIP1/RIP3 pathway analysis, mouse SJS/TEN model; radioligand competition, internalization, blockade, and Akt/phagocytosis assays for FAM19A4\",\n      \"pmids\": [\"25031270\", \"25109685\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How FPR1 selects necroptotic versus chemotactic outputs unresolved\", \"FAM19A4 binding site on FPR1 not mapped\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Showed a physical FPR1-uPAR-integrin signaling module at the cell surface, with co-IP and co-localization linking uPAR-dependent migration to intact FPR1 interaction.\",\n      \"evidence\": \"Co-IP, confocal co-localization, uPAR siRNA, antibody blocking, migration in transfected HEK293 cells\",\n      \"pmids\": [\"24466048\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single Co-IP system without reciprocal validation in primary cells\", \"Stoichiometry of the FPR1/uPAR/integrin complex unknown\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Generalized the tumor-promoting signaling program beyond glioblastoma, showing reciprocal gain/loss-of-function FPR1 control of neuroblastoma tumorigenesis via MAPK/ERK, PI3K/Akt, and p38 pathways.\",\n      \"evidence\": \"Calcium flux, phospho-immunoblots, cyclosporin H, shRNA and overexpression with xenografts in neuroblastoma cells\",\n      \"pmids\": [\"27432059\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Endogenous tumor ligand source not defined\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Identified a regulatory route for receptor desensitization, showing exogenous CO promotes FPR1 internalization through p38 MAPK rather than GRK2 to suppress neutrophil recruitment.\",\n      \"evidence\": \"Migration assays, FPR1 internalization studies, p38 versus GRK2 inhibition in neutrophils\",\n      \"pmids\": [\"27144520\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Molecular target of CO upstream of FPR1 internalization unclear\", \"Single lab\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Revealed FPR1 as a pathogen-exploited entry portal and a beneficial commensal sensor, with Y. pestis LcrV binding FPR1 to enable T3SS translocation (loss-of-function protective) and gut FPR1 transducing commensal LGG signals into neuronal ROS and motility.\",\n      \"evidence\": \"LcrV-FPR1 binding, Fpr1-/- infection and survival, human FPR1R190W neutrophil assay; Fpr1-KO mouse gut model with FISH, ROS/p-MAPK1 readouts and GI motility\",\n      \"pmids\": [\"31534221\", \"30930024\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"LcrV binding site on FPR1 not structurally mapped\", \"Commensal-derived formyl peptide ligand in gut not chemically defined\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Demonstrated cell-intrinsic, tissue-specific recruitment roles in fibrosis and immunosurveillance, with FPR1 required for neutrophil-driven bleomycin lung fibrosis and for dendritic-cell ANXA1 sensing in anthracycline-induced immunogenic cell death.\",\n      \"evidence\": \"Fpr1-/- bleomycin model with neutrophil adoptive transfer and multi-organ comparison; Fpr1-/- tumor models, DC/T-cell assays, pIC rescue, carcinogenesis model\",\n      \"pmids\": [\"32102985\", \"33046534\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Opposing protective (anticancer immunity) versus pathogenic (fibrosis) roles not mechanistically reconciled\", \"Determinants of tissue specificity unknown\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Characterized pharmacological tractability and biased signaling, with the FPR1-specific agonist RE-04-001 activating PLC-Ca2+ and ERK while minimally recruiting \\u03b2-arrestin, demonstrating that FPR1 effector arms can be selectively engaged.\",\n      \"evidence\": \"Ca2+ flux, superoxide, ERK, and \\u03b2-arrestin recruitment assays in FPR1/FPR2 cells and neutrophils\",\n      \"pmids\": [\"33040403\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Structural basis of biased agonism not defined\", \"In vivo consequences of arrestin-sparing signaling untested\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Linked FPR1 dysfunction to disease pathophysiology, showing high glucose impairs FPR-mediated chemotaxis to delay diabetic wound neutrophil trafficking, and FPR1 promotes post-stroke leukocyte brain infiltration and worse outcomes.\",\n      \"evidence\": \"Diabetic Lepr db/db model with in vitro glucose exposure and CCL3 rescue; focal ischemia in Fpr1-/- mice with cFLFLF antagonist and migration assays\",\n      \"pmids\": [\"35112667\", \"35547761\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Molecular mechanism of glucose-induced FPR signaling impairment incompletely defined\", \"Single labs\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How FPR1 selects between divergent functional outputs — chemotaxis, oxidase activation, necroptosis, tumor growth, and protective anticancer immunity — from the same Gi-coupled receptor remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No structural model of agonist-bound FPR1 in the corpus\", \"Determinants of ligand-biased and tissue-specific output not established\", \"Identity of many endogenous tumor and tissue agonists unknown\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0060089\", \"supporting_discovery_ids\": [0, 3, 17]},\n      {\"term_id\": \"GO:0001618\", \"supporting_discovery_ids\": [27]},\n      {\"term_id\": \"GO:0004930\", \"supporting_discovery_ids\": [0]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [1, 24]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [0, 2, 25]},\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [3, 17, 21, 29]},\n      {\"term_id\": \"R-HSA-1643685\", \"supporting_discovery_ids\": [19, 22, 27, 30]},\n      {\"term_id\": \"R-HSA-5357801\", \"supporting_discovery_ids\": [22, 29]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"ANXA1\", \"FAM19A4\", \"PLAUR\", \"ITGAV\", \"EGFR\", \"NTRK1\", \"LcrV\"],\n    \"other_free_text\": []\n  }\n}\n```","audit_flag":null,"evaluation":{"pairwise":"tie","faith_supported":7,"faith_total":7,"faith_pct":100.0}}