{"gene":"FPR1","run_date":"2026-04-28T17:46:04","timeline":{"discoveries":[{"year":2009,"finding":"FPR1 is a seven-transmembrane, G protein-coupled receptor expressed mainly on phagocytic leukocytes that binds N-formyl peptides (including fMLF) as well as annexin 1 and its N-terminal fragments, mediating chemotaxis and activation of phagocytes; the receptor family shares significant sequence homology with FPR2/ALX and FPR3.","method":"Pharmacological characterization, radioligand binding, functional assays in transfected cells","journal":"Pharmacological reviews","confidence":"High","confidence_rationale":"Tier 1–2 — comprehensive multi-lab pharmacological review with multiple orthogonal methods, replicated across labs","pmids":["19498085"],"is_preprint":false},{"year":2000,"finding":"Annexin I (lipocortin I) acts as an endogenous ligand of FPR1 on human neutrophils; N-terminal peptides of annexin I bind FPR and trigger Ca2+ transients and MAP kinase signaling in a dose-dependent manner, and at lower concentrations specifically inhibit transendothelial migration and desensitize neutrophils toward chemoattractant challenge.","method":"Radioligand competition binding, Ca2+ flux assays, transendothelial migration assays, MAP kinase activation assays in primary human neutrophils","journal":"Molecular cell","confidence":"High","confidence_rationale":"Tier 1–2 — multiple orthogonal methods (binding, signaling, functional migration assay), foundational paper with high citations","pmids":["10882119"],"is_preprint":false},{"year":1994,"finding":"FMLP stimulation of FPR1 on human neutrophils activates Ras and Raf-1 kinase through a pertussis toxin-sensitive Gi2 protein, leading to MEK-1 and MAP kinase activation independently of protein kinase C, suggesting Gi2-mediated receptor signaling through the Ras/Raf/MAP kinase pathway.","method":"Immunoprecipitation kinase assays, [32P]GTP labeling of Ras, pertussis toxin inhibition, in vitro MEK phosphorylation assay","journal":"The Journal of clinical investigation","confidence":"High","confidence_rationale":"Tier 1–2 — multiple orthogonal biochemical methods, pertussis toxin epistasis, highly cited foundational paper","pmids":["8040337"],"is_preprint":false},{"year":1997,"finding":"FMLP acting through FPR1 on human neutrophils activates p38 MAPK via MKK3, activates ERK (p42/44 MAPK) via pertussis toxin-sensitive G protein and MEKK1/Raf, but does not activate JNKs; p38 MAPK inhibition blocks superoxide production, adhesion, and chemotaxis downstream of FPR1.","method":"Kinase activity assays, immunoprecipitation, pertussis toxin inhibition, p38 MAPK inhibitor (SK&F 86002), functional neutrophil assays","journal":"The Journal of clinical investigation","confidence":"High","confidence_rationale":"Tier 1–2 — multiple orthogonal methods, distinct signaling pathway dissection","pmids":["9062356"],"is_preprint":false},{"year":2003,"finding":"In vivo, annexin 1 peptide Ac2-26 inhibits leukocyte adhesion and emigration through both FPR1 and ALXR (FPR2); in FPR1-deficient mice, Ac2-26 retains ~50% inhibitory activity blocked by the FPR antagonist Boc2, while FPR1-deficient neutrophils still express ALXR and respond to lipoxin A4 and Ac2-26 to detach adherent leukocytes.","method":"Intravital microscopy of mouse mesenteric microcirculation I/R model, FPR1-knockout mice, receptor antagonist pharmacology, RT-PCR and protein detection of ALXR","journal":"Blood","confidence":"High","confidence_rationale":"Tier 2 — genetic knockout combined with pharmacological antagonism and in vivo functional readout, replicated with multiple tools","pmids":["12560218"],"is_preprint":false},{"year":2005,"finding":"Human mitochondria-derived N-formylated hexapeptides (fMMYALF, fMLKLIV, fMFADRW) are potent agonists equally active on FPR1 and FPRL1 (EC50 ~10–160 nM), whereas Listeria monocytogenes-derived bacterial peptides are 100-fold more potent on FPR1 than FPRL1; none activate FPRL2.","method":"Fura-2 calcium mobilization assays in HL-60 cell lines stably transfected with FPR1, FPRL1, or FPRL2; chemotaxis assays","journal":"European journal of immunology","confidence":"High","confidence_rationale":"Tier 1–2 — quantitative receptor-specific functional assays with multiple peptides and transfected cell lines","pmids":["16025565"],"is_preprint":false},{"year":2010,"finding":"Mitochondrial degradation products activate human neutrophils via FPR1 (not FPRL1); anti-FPR1 antibody completely blocked mitochondrial peptide-induced intracellular Ca2+ responses, and mitochondrial peptides induced FPR1-dependent chemotaxis and oxidative burst comparable to fMLF.","method":"Cytosolic Ca2+ measurements with antibody blockade of FPR1 vs FPRL1, trans-well chemotaxis assays, oxidative burst assay with carboxycarboxy-2',7'-dichlorodihydrofluorescein diacetate","journal":"The Journal of trauma","confidence":"High","confidence_rationale":"Tier 2 — specific antibody blockade differentiating FPR1 vs FPRL1, multiple orthogonal functional readouts","pmids":["20539176"],"is_preprint":false},{"year":1999,"finding":"Mouse FPR2 (encoded by Fpr-rs2) is a low-affinity N-formylpeptide receptor expressed on neutrophils; fMLF induces two distinct concentration optima for chemotaxis in normal mouse neutrophils (high- and low-affinity), but only the high-concentration optimum in FPR1-knockout neutrophils, establishing FPR1 as the high-affinity fMLF receptor mediating the lower-concentration chemotaxis response.","method":"HEK293 stable transfection, Ca2+ flux, chemotaxis assays, FPR knockout mouse neutrophils","journal":"The Journal of experimental medicine","confidence":"High","confidence_rationale":"Tier 2 — genetic knockout epistasis combined with transfected cell functional assays","pmids":["10477558"],"is_preprint":false},{"year":2005,"finding":"FPR1 expressed by glioblastoma cell line U-87 mediates chemotaxis (increased motility), cell proliferation, and VEGF production in response to fMLF; FPR1 siRNA knockdown substantially reduced tumorigenicity in nude mice and revealed that necrotic glioblastoma cells release endogenous FPR1 agonists.","method":"RT-PCR, chemotaxis assay, siRNA knockdown, BrdU proliferation, xenograft nude mouse model, ELISA for VEGF","journal":"Journal of the National Cancer Institute","confidence":"High","confidence_rationale":"Tier 2 — loss-of-function (siRNA) with multiple phenotypic readouts and in vivo xenograft validation","pmids":["15928303"],"is_preprint":false},{"year":2014,"finding":"Annexin A1 released by drug-stimulated PBMCs activates FPR1 on SJS/TEN keratinocytes to trigger necroptosis via RIP1-RIP3 complex formation; SJS/TEN keratinocytes specifically upregulate FPR1 expression, and inhibition of necroptosis or absence of FPR1-annexed A1 signaling prevented keratinocyte death.","method":"Mass spectrometry identification of annexin A1, antibody depletion, RIP1/RIP3 complex detection, immunostaining for FPR1, mouse SJS/TEN model with necroptosis inhibitor","journal":"Science translational medicine","confidence":"High","confidence_rationale":"Tier 2 — mass spectrometry identification, antibody depletion, KO model, multiple mechanistic steps validated","pmids":["25031270"],"is_preprint":false},{"year":2019,"finding":"LcrV, the needle cap protein of Yersinia pestis type III secretion system, binds FPR1 on human immune cells to facilitate translocation of bacterial effectors; Fpr1-deficient mice show increased survival from plague infection, and the FPR1-R190W variant in humans confers resistance to Y. pestis-mediated neutrophil destruction.","method":"Protein-receptor binding studies, Fpr1-knockout mouse infection model, functional assays with FPR1-R190W variant neutrophils","journal":"Nature","confidence":"High","confidence_rationale":"Tier 2 — genetic knockout in vivo model, human variant functional validation, highly cited","pmids":["31534221"],"is_preprint":false},{"year":2007,"finding":"Downstream of the fMLF-FPR1 receptor, Rac1 mediates uncapping of existing actin free barbed ends (FBE), whereas Rac2 regulates cofilin-mediated severing and ARP2/3-mediated de novo nucleation; relative contributions are uncapping 15%, cofilin severing 10%, ARP2/3 nucleation 75%.","method":"Neutrophils from Rac1- or Rac2-deficient mice, neutrophil permeabilization model maintaining receptor signaling, actin free barbed end assay","journal":"The Journal of cell biology","confidence":"High","confidence_rationale":"Tier 2 — genetic knockout cells combined with biochemical actin dynamics assay dissecting distinct mechanisms","pmids":["17954607"],"is_preprint":false},{"year":2001,"finding":"The endogenous opioid spinorphin acts as a specific competitive antagonist at FPR1: it induces Ca2+ flux in normal mouse neutrophils and FPR1-transfected HEK293 cells but is inactive in FPR1-knockout neutrophils and FPR2-expressing cells, and blocks fMLF-induced FPR1-selective chemotaxis without affecting FPR2-selective responses.","method":"Ca2+ flux assays, FPR1-knockout mouse neutrophils, FPR1- and FPR2-transfected HEK293 cells, chemotaxis assays","journal":"Journal of immunology","confidence":"High","confidence_rationale":"Tier 2 — gain- and loss-of-function genetics (KO + transfection) with functional assays","pmids":["11714831"],"is_preprint":false},{"year":2012,"finding":"FPR1 is required for effective neutrophil recruitment to the damaged lung; Fpr1-/- mice are protected from bleomycin-induced pulmonary fibrosis due to failure to recruit neutrophils, and adoptive transfer shows this defect is intrinsic to fpr1-/- neutrophils rather than the lung environment.","method":"Fpr1 knockout mice, bleomycin lung fibrosis model, adoptive transfer of wild-type neutrophils into fpr1-/- mice, cell counting","journal":"JCI insight","confidence":"High","confidence_rationale":"Tier 2 — knockout mouse model with adoptive transfer demonstrating cell-intrinsic mechanism","pmids":["32102985"],"is_preprint":false},{"year":2019,"finding":"FPR1 is required in the enteric nervous system for commensal bacteria (LGG)-mediated increases in GI motility; LGG-induced myenteric ROS production, MAPK1 phosphorylation, and increased choline acetyltransferase expression are absent in FPR1-knockout mice, and require bacterial adhesion.","method":"FPR1-knockout mice, germ-free mice, gavage experiments, immunoblots, immunostaining, fluorescence in situ hybridization, ex vivo muscle contraction assays","journal":"Gastroenterology","confidence":"High","confidence_rationale":"Tier 2 — genetic knockout with multiple mechanistic readouts and in vivo functional consequence","pmids":["30930024"],"is_preprint":false},{"year":2020,"finding":"For anthracycline-based chemotherapy to be immunogenic, dying cancer cells release annexin A1 (ANXA1) which interacts with FPR1 on dendritic cells; FPR1-deficient mice show deficient chemotherapeutic responses and earlier cancer development, and FPR1 loss-of-function alleles are associated with earlier cancer development in humans.","method":"FPR1-knockout mouse tumor models, dendritic cell and T-cell functional assays, ANXA1-knockout tumor models, human clinical data for FPR1 alleles","journal":"Cancer discovery","confidence":"High","confidence_rationale":"Tier 2 — multiple genetic models (FPR1-KO, ANXA1-KO) with mechanistic immune readouts","pmids":["33046534"],"is_preprint":false},{"year":2012,"finding":"FPR1 activation by fMLF in glioblastoma cells transactivates EGFR and promotes glioma cell chemotaxis, invasion, growth, and production of angiogenic factors; this is triggered by endogenous agonist annexin A1 released by necrotic glioma cells.","method":"RT-PCR, flow cytometry, siRNA, chemotaxis assay, EGFR transactivation assays, xenograft mouse model","journal":"International immunopharmacology","confidence":"Medium","confidence_rationale":"Tier 2–3 — mechanistic pathway placement (FPR1→EGFR transactivation) but primary data cited from prior work; review with limited new experimental data","pmids":["22863814"],"is_preprint":false},{"year":1994,"finding":"The NH2-terminal extracellular domain of FPR1 is not critical for plasma membrane transport or high-affinity N-formyl peptide binding; replacing the NH2-terminal domain of FPR1 with that of C5aR or FPRH resulted in normal cell surface expression and ligand binding, establishing that the FPR1 N-terminus is dispensable for receptor folding/transport.","method":"C5aR/FPR chimeric receptor construction, transfection into cells, radioligand binding assays, immunofluorescence for membrane localization","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 — reconstitution with chimeric receptors and mutagenesis with direct functional and localization readouts","pmids":["8106386"],"is_preprint":false},{"year":1990,"finding":"FMLP-induced protein kinase C translocation (membrane association) and superoxide generation in human neutrophils are both dependent on a pertussis toxin-sensitive G protein, whereas PMA-, ionomycin-, or A23187-induced PKC translocation and superoxide generation are pertussis toxin-insensitive, placing FPR1 upstream of a Gi-dependent PKC activation cascade.","method":"Pertussis toxin pretreatment, subcellular fractionation for PKC activity, superoxide generation assay","journal":"Journal of leukocyte biology","confidence":"Medium","confidence_rationale":"Tier 2 — pharmacological dissection with pertussis toxin; single lab, single primary method","pmids":["2152941"],"is_preprint":false},{"year":2011,"finding":"FPR1 (not FPR2 or FPR3) is upregulated during osteoblastic differentiation of human bone marrow mesenchymal stem cells; fMLP acting through FPR1 promotes osteoblastic commitment via FPR1-PLC/PLD-Ca2+-CaMKII-ERK-CREB signaling and suppresses adipogenic commitment, with FPR1 antagonist cyclosporine H blocking these effects.","method":"qPCR, flow cytometry for FPR expression, calcium mobilization, western blot for phospho-signaling, siRNA knockdown, osteogenic/adipogenic differentiation assays, zebrafish and rabbit in vivo bone formation","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 — multiple orthogonal methods defining signaling pathway, in vitro and in vivo validation","pmids":["21372136"],"is_preprint":false},{"year":2016,"finding":"FPR1 expressed in neuroblastoma cells mediates calcium mobilization and activates MAPK/Erk, PI3K/Akt, and p38-MAPK signaling upon fMLP stimulation; FPR1 shRNA knockdown delayed xenograft tumor development, while FPR1 overexpression promoted tumorigenesis in nude mice.","method":"Calcium mobilization assay, phospho-specific western blots, shRNA knockdown, cDNA overexpression, nude mouse xenograft model","journal":"BMC cancer","confidence":"High","confidence_rationale":"Tier 2 — loss- and gain-of-function with in vivo tumor model and mechanistic signaling pathway data","pmids":["27432059"],"is_preprint":false},{"year":2016,"finding":"FPR1 mediates neutrophil recruitment to LPS-induced lung injury and jointly with CCR5 orchestrates neutrophil infiltration; Fpr1-/- mice or mice treated with FPR1 antagonist showed reduced neutrophil counts in all lung compartments, reduced edema, and reduced histological lung damage.","method":"Fpr1-knockout mice, LPS aerosol model, pharmacological FPR1 antagonist, lung compartment neutrophil counting","journal":"Journal of innate immunity","confidence":"Medium","confidence_rationale":"Tier 2 — genetic knockout with pharmacological validation and defined cellular phenotype","pmids":["23860188"],"is_preprint":false},{"year":2005,"finding":"The uPAR-derived SRSRY peptide stimulates cell migration and F-actin polarization via FPR1; fMLF at 100 nM inhibits SRSRY-stimulated migration, and SRSRY promotes FPR1-dependent vitronectin release and increased uPAR·αvβ5 vitronectin receptor association, with αvβ5 required for ERK1/2 phosphorylation downstream of FPR1.","method":"Chemotaxis assays with alanine-substituted SRSRY analogues, F-actin staining, competitive binding with fMLF, ERK1/2 phosphorylation, co-immunoprecipitation of uPAR and αvβ5","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2–3 — multiple functional assays and co-IP, but signaling pathway partly inferred from inhibitor studies","pmids":["15866865"],"is_preprint":false},{"year":2020,"finding":"The small compound RE-04-001 specifically activates FPR1 at very low concentrations (EC50 ~1 nM for NADPH-oxidase activation) and is a biased agonist that strongly activates the PLC-PIP2-Ca2+ pathway and ERK1/2 but shows minimal β-arrestin recruitment and requires higher concentrations for chemotaxis, demonstrating functional selectivity downstream of FPR1.","method":"Ca2+ flux, ROS measurement, β-arrestin recruitment assay (BRET), chemotaxis assay, receptor-specific pharmacological antagonists in human neutrophils and HL-60 cells","journal":"Journal of leukocyte biology","confidence":"Medium","confidence_rationale":"Tier 2 — multiple assays showing biased signaling, single lab","pmids":["33040403"],"is_preprint":false},{"year":2012,"finding":"Molecular dynamics simulations of FPR1 modeled on the CXCR4 template reveal that receptor activation involves a water molecule transiently bridging a hydrogen bond between W254(6.48) and N108(3.35), and a rotamer switch of Y301(7.53) facilitates movement of water molecules toward the receptor center, with agonist fMLF contacting R201(5.38) and R205(5.42) on TM5.","method":"Homology modeling using CXCR4 as template, molecular dynamics simulations of FPR1 with agonist fMLF and antagonist tBocMLF in model membrane","journal":"PloS one","confidence":"Low","confidence_rationale":"Tier 4 — computational modeling only, no experimental mutagenesis or structural validation","pmids":["23189124"],"is_preprint":false},{"year":2022,"finding":"FPR1 is required for splenocyte migration into ischemic brain tissue; FPR1 antagonist cFLFLFK inhibited splenocyte and monocyte/neutrophil brain infiltration and neuroinflammatory cytokine production, and fpr1-/- mice showed reduced peripheral immune cell infiltration into brain with improved neurological outcomes after stroke.","method":"Fpr1-knockout mice, transient focal brain ischemia model, FPR1 antagonist cFLFLFK, in vitro and in vivo splenocyte migration assays, cytokine measurement, neurological scoring","journal":"Theranostics","confidence":"Medium","confidence_rationale":"Tier 2 — genetic knockout plus pharmacological blockade with functional brain injury readouts","pmids":["35547761"],"is_preprint":false},{"year":2022,"finding":"Exposure to diabetic-range glucose impairs FPR chemotaxis signaling in neutrophils, leading to reduced chemotaxis and delayed neutrophil trafficking in wounds of Lepr(db/db) diabetic mice; CCL3 engagement of auxiliary receptors overrides the FPR signaling requirement and restores infection control.","method":"Human neutrophil chemotaxis assays at elevated glucose, Lepr(db/db) mouse wound infection model, CCL3 supplementation rescue experiments","journal":"eLife","confidence":"Medium","confidence_rationale":"Tier 2 — in vitro and in vivo functional assays with genetic diabetic model and pathway rescue","pmids":["35112667"],"is_preprint":false},{"year":2017,"finding":"FPR1 blockade by cyclosporine H (CsH) inhibits neutrophil accumulation at necrotic areas in the liver during ischemia-reperfusion injury; two-photon intravital microscopy demonstrated that FPR1 signaling regulates neutrophil chemotaxis and crawling velocity into necrotic zones while not affecting monocyte/macrophage recruitment.","method":"Two-photon laser-scanning microscopy in LysM-eGFP mice, FPR1 antagonist CsH, hepatic I/R model, serum transaminases, histology","journal":"Journal of immunology","confidence":"Medium","confidence_rationale":"Tier 2 — live intravital imaging with pharmacological FPR1 blockade, single lab","pmids":["28062700"],"is_preprint":false},{"year":2015,"finding":"A pepducin derived from the third intracellular loop of FPR1 inhibits neutrophil superoxide production and granule mobilization, but acts by selectively targeting FPR2 (not FPR1 as designed); the fatty acid moiety is essential for inhibition and the compound blocks FPR2 agonist binding to neutrophil surfaces.","method":"Superoxide production assay, granule mobilization assay, receptor-specific desensitization, FPR2 agonist binding competition in human neutrophils","journal":"FEBS letters","confidence":"Medium","confidence_rationale":"Tier 2–3 — receptor selectivity determined by multiple functional assays, single lab","pmids":["26071379"],"is_preprint":false},{"year":2016,"finding":"Exogenous CO (via CORM-2) inhibits LPS-stimulated neutrophil migration toward fMLF by internalizing FPR1 through a p38 MAPK-dependent (not GRK2-dependent) mechanism.","method":"Affymetrix gene chip array, under-agarose migration assay, western blot for FPR1 internalization and p38 MAPK/GRK2 phosphorylation, in vivo LPS sepsis mouse model","journal":"Oncotarget","confidence":"Medium","confidence_rationale":"Tier 2–3 — biochemical mechanism with functional readout, single lab","pmids":["27144520"],"is_preprint":false}],"current_model":"FPR1 is a seven-transmembrane Gi-coupled GPCR on phagocytic leukocytes that recognizes N-formyl peptides from bacteria and mitochondria, as well as endogenous ligands including annexin A1, and upon ligand binding activates Gi2-dependent Ras/Raf/ERK and p38 MAPK signaling cascades, Rac1/Rac2-regulated actin remodeling for chemotaxis, NADPH oxidase for superoxide production, and—in glioblastoma cells—transactivates EGFR to drive invasion and angiogenesis; FPR1 also serves as the entry receptor for Yersinia pestis type III secretion on immune cells, and its interaction with annexin A1 on dendritic cells is required for immunogenic cell death during anthracycline chemotherapy."},"narrative":{"teleology":[{"year":1990,"claim":"The first signaling step downstream of FPR1 was placed at a pertussis toxin-sensitive G protein coupling to both PKC translocation and superoxide generation, establishing that FPR1 signals through Gi-family proteins in neutrophils.","evidence":"Pertussis toxin pretreatment of human neutrophils with subcellular PKC fractionation and superoxide assay","pmids":["2152941"],"confidence":"Medium","gaps":["Gi subtype not identified","no direct receptor–G protein biochemistry"]},{"year":1994,"claim":"The downstream MAPK cascade was delineated: FPR1 activates Ras→Raf-1→MEK-1→ERK through Gi2, independent of PKC, establishing a canonical mitogenic signaling arm for a chemoattractant receptor.","evidence":"Immunoprecipitation kinase assays, GTP-Ras pull-down, pertussis toxin epistasis in human neutrophils","pmids":["8040337"],"confidence":"High","gaps":["how Gi2 βγ subunits activate Ras was unresolved","p38 MAPK arm not yet tested"]},{"year":1994,"claim":"Chimeric receptor studies showed the FPR1 N-terminal extracellular domain is dispensable for ligand binding and membrane trafficking, redirecting attention to transmembrane and extracellular loop determinants of formyl-peptide recognition.","evidence":"C5aR/FPR and FPRH/FPR chimeric receptor transfection with radioligand binding and immunofluorescence","pmids":["8106386"],"confidence":"High","gaps":["specific ligand-contact residues in TM domains not mapped experimentally"]},{"year":1997,"claim":"A parallel p38 MAPK pathway (via MKK3) was resolved as essential for FPR1-dependent superoxide, adhesion, and chemotaxis, while JNK was excluded, completing the bifurcation of FPR1 into ERK and p38 effector arms.","evidence":"Kinase assays, immunoprecipitation, and p38 inhibitor SK&F 86002 in human neutrophils","pmids":["9062356"],"confidence":"High","gaps":["how p38 specifically controls NADPH oxidase vs. adhesion was unclear"]},{"year":1999,"claim":"Knockout mouse studies proved FPR1 is the high-affinity fMLF receptor mediating low-concentration chemotactic responses, resolving pharmacological ambiguity about receptor identity in mouse neutrophils.","evidence":"Fpr1-knockout mouse neutrophils, two-optimum chemotaxis assay, HEK293 transfection","pmids":["10477558"],"confidence":"High","gaps":["mouse Fpr gene family complexity left ligand selectivity of Fpr-rs2 incompletely defined"]},{"year":2000,"claim":"Annexin A1 was identified as an endogenous FPR1 ligand that at low concentrations desensitizes neutrophils and inhibits transendothelial migration, establishing FPR1 as a receptor with dual pro- and anti-inflammatory signaling capacity depending on ligand concentration.","evidence":"Radioligand competition, Ca²⁺ flux, MAP kinase, and transendothelial migration assays in primary human neutrophils","pmids":["10882119"],"confidence":"High","gaps":["precise structural determinants of bimodal signaling unresolved","in vivo relevance of annexin A1–FPR1 axis not yet tested"]},{"year":2003,"claim":"In vivo validation using Fpr1-knockout mice in an ischemia-reperfusion model showed annexin A1 peptide Ac2-26 acts through both FPR1 and FPR2/ALX to inhibit leukocyte trafficking, quantifying ~50% of anti-inflammatory activity as FPR1-dependent.","evidence":"Intravital microscopy of mesenteric microcirculation in Fpr1-KO mice with pharmacological antagonists","pmids":["12560218"],"confidence":"High","gaps":["relative contribution of FPR1 vs FPR2 varies by tissue and model"]},{"year":2005,"claim":"Mitochondrial N-formyl peptides were shown to be potent FPR1 agonists comparable to bacterial peptides, establishing that FPR1 senses host-derived danger signals from mitochondrial damage, while bacterial formyl peptides showed 100-fold FPR1 selectivity over FPRL1.","evidence":"Ca²⁺ mobilization and chemotaxis in HL-60 lines stably expressing FPR1, FPRL1, or FPRL2","pmids":["16025565"],"confidence":"High","gaps":["in vivo significance of mitochondrial DAMPs acting through FPR1 not yet demonstrated"]},{"year":2005,"claim":"FPR1 expression was discovered on glioblastoma cells where it drives tumor motility, proliferation, and VEGF production, extending FPR1 biology beyond innate immunity to cancer.","evidence":"siRNA knockdown with chemotaxis, BrdU, VEGF ELISA, and nude mouse xenograft","pmids":["15928303"],"confidence":"High","gaps":["identity of endogenous glioma-derived FPR1 agonist not fully characterized"]},{"year":2007,"claim":"The cytoskeletal effectors downstream of FPR1 were dissected: Rac2 controls ARP2/3-dependent nucleation (~75% of actin assembly) and cofilin-mediated severing, while Rac1 regulates barbed-end uncapping, explaining how FPR1 coordinates directional actin polymerization for chemotaxis.","evidence":"Permeabilized neutrophils from Rac1- or Rac2-knockout mice with actin free barbed end assays","pmids":["17954607"],"confidence":"High","gaps":["upstream GEFs linking Gi to Rac1 vs Rac2 activation not identified"]},{"year":2010,"claim":"Antibody blockade definitively attributed mitochondrial DAMP-induced neutrophil activation (Ca²⁺, chemotaxis, oxidative burst) to FPR1 rather than FPRL1, confirming FPR1 as the primary mitochondrial danger receptor on neutrophils in trauma.","evidence":"Anti-FPR1 vs anti-FPRL1 blocking antibodies with Ca²⁺, chemotaxis, and ROS assays","pmids":["20539176"],"confidence":"High","gaps":["specific mitochondrial peptide sequences driving in vivo sterile inflammation not mapped"]},{"year":2011,"claim":"FPR1 was found to direct mesenchymal stem cell fate: activation promotes osteoblastic over adipogenic differentiation via PLC/PLD-Ca²⁺-CaMKII-ERK-CREB signaling, revealing a non-immune developmental role.","evidence":"FPR1 expression profiling, siRNA, calcium mobilization, phospho-signaling, in vivo zebrafish and rabbit bone formation","pmids":["21372136"],"confidence":"High","gaps":["physiological source of formyl peptides in bone marrow niche unknown"]},{"year":2014,"claim":"FPR1 was identified as the receptor through which annexin A1 triggers necroptosis in keratinocytes during Stevens-Johnson syndrome/toxic epidermal necrolysis, via RIP1-RIP3 complex formation.","evidence":"Mass spectrometry of PBMC secretome, antibody depletion, RIP1/RIP3 detection, mouse SJS/TEN model with necroptosis inhibitor","pmids":["25031270"],"confidence":"High","gaps":["why keratinocytes upregulate FPR1 in SJS/TEN is mechanistically unexplained","whether FPR1 directly activates necroptosis machinery or signals through intermediate kinases not defined"]},{"year":2019,"claim":"FPR1 was shown to function in enteric neurons, transducing commensal bacterial signals (Lactobacillus GG) into ROS production, MAPK1 phosphorylation, and increased cholinergic neurotransmission to regulate GI motility.","evidence":"Fpr1-KO and germ-free mice, gavage, immunoblots, FISH, ex vivo muscle contraction","pmids":["30930024"],"confidence":"High","gaps":["specific bacterial formyl peptides responsible not identified","mechanism of FPR1-to-ROS coupling in neurons not delineated"]},{"year":2019,"claim":"FPR1 was revealed as the host receptor exploited by Yersinia pestis LcrV for type III secretion effector delivery into immune cells; Fpr1-deficient mice resist plague and the human FPR1-R190W variant confers neutrophil resistance.","evidence":"Protein–receptor binding, Fpr1-KO mouse plague infection, human R190W variant neutrophil functional assays","pmids":["31534221"],"confidence":"High","gaps":["structural basis of LcrV–FPR1 interaction unresolved","whether other pathogens exploit FPR1 similarly not tested"]},{"year":2020,"claim":"FPR1 on dendritic cells was established as essential for immunogenic cell death during anthracycline chemotherapy: dying cancer cells release annexin A1, which activates DC FPR1 to enable antitumor immunity; FPR1 loss-of-function alleles associate with worse cancer outcomes in humans.","evidence":"FPR1-KO and ANXA1-KO tumor mouse models, DC and T-cell assays, human clinical allele data","pmids":["33046534"],"confidence":"High","gaps":["downstream signaling in DCs linking FPR1 to antigen cross-presentation not mapped","whether FPR1 allele effect extends beyond anthracycline regimens unknown"]},{"year":2020,"claim":"Biased agonism at FPR1 was demonstrated: compound RE-04-001 potently activates PLC-Ca²⁺ and ERK but minimally recruits β-arrestin, showing that FPR1 signaling outputs are dissociable and ligand-dependent.","evidence":"Ca²⁺ flux, ROS, BRET β-arrestin recruitment, chemotaxis in neutrophils and HL-60 cells","pmids":["33040403"],"confidence":"Medium","gaps":["structural basis for biased signaling at FPR1 unknown","single compound; generalizability to other biased ligands not shown"]},{"year":null,"claim":"High-resolution structural data for FPR1 bound to diverse ligands (formyl peptides, annexin A1, LcrV) are needed to explain ligand selectivity, biased agonism, and the pathogen exploitation mechanism, and the signaling events downstream of FPR1 on dendritic cells that link to antigen cross-presentation remain undefined.","evidence":"","pmids":[],"confidence":"Low","gaps":["no experimental FPR1 structure in the timeline","GEFs coupling Gi to Rac1/Rac2 not identified","DC-intrinsic FPR1 signaling cascade for immunogenic cell death unknown"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0060089","term_label":"molecular transducer activity","supporting_discovery_ids":[0,5,7,10]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[1,4,15]}],"localization":[{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[0,17,7]}],"pathway":[{"term_id":"R-HSA-168256","term_label":"Immune System","supporting_discovery_ids":[0,2,3,6,11,13,21]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[2,3,19,20,23]},{"term_id":"R-HSA-1643685","term_label":"Disease","supporting_discovery_ids":[8,10,16,20]}],"complexes":[],"partners":["ANXA1","GNAI2","RAC1","RAC2","EGFR","MAPK14","MAPK1"],"other_free_text":[]},"mechanistic_narrative":"FPR1 is a Gi-coupled seven-transmembrane receptor that senses N-formyl peptides from bacteria and mitochondria as well as the endogenous ligand annexin A1, functioning as a master chemotactic receptor that directs phagocyte recruitment to sites of infection, tissue damage, and sterile inflammation. Ligand binding activates pertussis toxin-sensitive Gi2 signaling through Ras/Raf/ERK and p38 MAPK cascades, PLC-mediated calcium mobilization, and Rac1/Rac2-dependent actin remodeling that together drive chemotaxis, NADPH oxidase-dependent superoxide production, and degranulation [PMID:8040337, PMID:9062356, PMID:17954607]. Beyond innate immunity, FPR1 on dendritic cells is required for immunogenic cell death signaling during anthracycline chemotherapy via annexin A1 recognition, and FPR1 serves as the entry receptor exploited by the Yersinia pestis type III secretion needle-cap protein LcrV, with Fpr1-deficient mice showing increased resistance to plague [PMID:33046534, PMID:31534221]. FPR1 is also expressed in non-immune contexts including glioblastoma and neuroblastoma cells, where it transactivates EGFR to promote tumor growth and angiogenesis, and in the enteric nervous system, where it transduces commensal bacterial signals to regulate gastrointestinal motility [PMID:15928303, PMID:30930024]."},"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":"12496257","id":"PMC_12496257","title":"Structure-function studies of the adipocyte-secreted hormone Acrp30/adiponectin. Implications fpr metabolic regulation and bioactivity.","date":"2002","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/12496257","citation_count":872,"is_preprint":false},{"pmid":"19498085","id":"PMC_19498085","title":"International Union of Basic and Clinical Pharmacology. LXXIII. Nomenclature for the formyl peptide receptor (FPR) family.","date":"2009","source":"Pharmacological reviews","url":"https://pubmed.ncbi.nlm.nih.gov/19498085","citation_count":653,"is_preprint":false},{"pmid":"9500793","id":"PMC_9500793","title":"Neutrophils emigrate from venules by a transendothelial cell pathway in response to FMLP.","date":"1998","source":"The Journal of experimental medicine","url":"https://pubmed.ncbi.nlm.nih.gov/9500793","citation_count":281,"is_preprint":false},{"pmid":"10882119","id":"PMC_10882119","title":"A novel ligand of the formyl peptide receptor: annexin I regulates neutrophil extravasation by interacting with the FPR.","date":"2000","source":"Molecular cell","url":"https://pubmed.ncbi.nlm.nih.gov/10882119","citation_count":270,"is_preprint":false},{"pmid":"9062356","id":"PMC_9062356","title":"Common and distinct intracellular signaling pathways in human neutrophils utilized by platelet activating factor and FMLP.","date":"1997","source":"The Journal of clinical investigation","url":"https://pubmed.ncbi.nlm.nih.gov/9062356","citation_count":240,"is_preprint":false},{"pmid":"11160457","id":"PMC_11160457","title":"Amyloid (beta)42 activates a G-protein-coupled chemoattractant receptor, FPR-like-1.","date":"2001","source":"The Journal of neuroscience : the official journal of the Society for Neuroscience","url":"https://pubmed.ncbi.nlm.nih.gov/11160457","citation_count":221,"is_preprint":false},{"pmid":"12560218","id":"PMC_12560218","title":"Leukocyte antiadhesive actions of annexin 1: ALXR- and FPR-related anti-inflammatory mechanisms.","date":"2003","source":"Blood","url":"https://pubmed.ncbi.nlm.nih.gov/12560218","citation_count":174,"is_preprint":false},{"pmid":"16025565","id":"PMC_16025565","title":"Human mitochondria-derived N-formylated peptides are novel agonists equally active on FPR and FPRL1, while Listeria monocytogenes-derived peptides preferentially activate FPR.","date":"2005","source":"European journal of immunology","url":"https://pubmed.ncbi.nlm.nih.gov/16025565","citation_count":169,"is_preprint":false},{"pmid":"8040337","id":"PMC_8040337","title":"FMLP activates Ras and Raf in human neutrophils. Potential role in activation of MAP kinase.","date":"1994","source":"The Journal of clinical investigation","url":"https://pubmed.ncbi.nlm.nih.gov/8040337","citation_count":154,"is_preprint":false},{"pmid":"10466071","id":"PMC_10466071","title":"Cellular responses to FMLP challenging: a mini-review.","date":"1999","source":"Immunopharmacology and immunotoxicology","url":"https://pubmed.ncbi.nlm.nih.gov/10466071","citation_count":117,"is_preprint":false},{"pmid":"15928303","id":"PMC_15928303","title":"Formylpeptide receptor FPR and the rapid growth of malignant human gliomas.","date":"2005","source":"Journal of the National Cancer Institute","url":"https://pubmed.ncbi.nlm.nih.gov/15928303","citation_count":110,"is_preprint":false},{"pmid":"20539176","id":"PMC_20539176","title":"Mitochondrial peptides are potent immune activators that activate human neutrophils via FPR-1.","date":"2010","source":"The Journal of trauma","url":"https://pubmed.ncbi.nlm.nih.gov/20539176","citation_count":110,"is_preprint":false},{"pmid":"25031270","id":"PMC_25031270","title":"An annexin A1-FPR1 interaction contributes to necroptosis of keratinocytes in severe cutaneous adverse drug reactions.","date":"2014","source":"Science translational medicine","url":"https://pubmed.ncbi.nlm.nih.gov/25031270","citation_count":106,"is_preprint":false},{"pmid":"2546043","id":"PMC_2546043","title":"The PEP: fructose phosphotransferase system in Salmonella typhimurium: FPr combines enzyme IIIFru and pseudo-HPr activities.","date":"1989","source":"Molecular & general genetics : MGG","url":"https://pubmed.ncbi.nlm.nih.gov/2546043","citation_count":97,"is_preprint":false},{"pmid":"17954607","id":"PMC_17954607","title":"Rac1 and Rac2 differentially regulate actin free barbed end formation downstream of the fMLP receptor.","date":"2007","source":"The Journal of cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/17954607","citation_count":95,"is_preprint":false},{"pmid":"10477558","id":"PMC_10477558","title":"N-formylpeptides induce two distinct concentration optima for mouse neutrophil chemotaxis by differential interaction with two N-formylpeptide receptor (FPR) subtypes. 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":94,"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":"6142713","id":"PMC_6142713","title":"Sulfasalazine inhibition of binding of N-formyl-methionyl-leucyl-phenylalanine (FMLP) to its receptor on human neutrophils.","date":"1984","source":"Biochemical pharmacology","url":"https://pubmed.ncbi.nlm.nih.gov/6142713","citation_count":87,"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":82,"is_preprint":false},{"pmid":"30930024","id":"PMC_30930024","title":"Interactions Between Commensal Bacteria and Enteric Neurons, via FPR1 Induction of ROS, Increase Gastrointestinal Motility in Mice.","date":"2019","source":"Gastroenterology","url":"https://pubmed.ncbi.nlm.nih.gov/30930024","citation_count":76,"is_preprint":false},{"pmid":"1372506","id":"PMC_1372506","title":"Tyrosine phosphorylation and its possible role in superoxide production by human neutrophils stimulated with FMLP and IgG.","date":"1992","source":"Biochemical and biophysical research communications","url":"https://pubmed.ncbi.nlm.nih.gov/1372506","citation_count":72,"is_preprint":false},{"pmid":"8106386","id":"PMC_8106386","title":"The NH2-terminal region of C5aR but not that of FPR is critical for both protein transport and ligand binding.","date":"1994","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/8106386","citation_count":65,"is_preprint":false},{"pmid":"32244997","id":"PMC_32244997","title":"Modulation of NLRP3 Inflammasome through Formyl Peptide Receptor 1 (Fpr-1) Pathway as a New Therapeutic Target in Bronchiolitis Obliterans Syndrome.","date":"2020","source":"International journal of molecular sciences","url":"https://pubmed.ncbi.nlm.nih.gov/32244997","citation_count":64,"is_preprint":false},{"pmid":"15866865","id":"PMC_15866865","title":"Cross-talk between fMLP and vitronectin receptors triggered by urokinase receptor-derived SRSRY peptide.","date":"2005","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/15866865","citation_count":63,"is_preprint":false},{"pmid":"18523971","id":"PMC_18523971","title":"Glioblastoma stem cells produce vascular endothelial growth factor by activation of a G-protein coupled formylpeptide receptor FPR.","date":"2008","source":"The Journal of pathology","url":"https://pubmed.ncbi.nlm.nih.gov/18523971","citation_count":61,"is_preprint":false},{"pmid":"22863814","id":"PMC_22863814","title":"G protein-coupled receptor FPR1 as a pharmacologic target in inflammation and human glioblastoma.","date":"2012","source":"International immunopharmacology","url":"https://pubmed.ncbi.nlm.nih.gov/22863814","citation_count":59,"is_preprint":false},{"pmid":"22461430","id":"PMC_22461430","title":"Genetic ablation of the fpr1 gene confers protection from smoking-induced lung emphysema in mice.","date":"2012","source":"American journal of respiratory cell and molecular biology","url":"https://pubmed.ncbi.nlm.nih.gov/22461430","citation_count":57,"is_preprint":false},{"pmid":"31534221","id":"PMC_31534221","title":"FPR1 is the plague receptor on host immune cells.","date":"2019","source":"Nature","url":"https://pubmed.ncbi.nlm.nih.gov/31534221","citation_count":56,"is_preprint":false},{"pmid":"20197768","id":"PMC_20197768","title":"The G-protein-coupled formylpeptide receptor FPR confers a more invasive phenotype on human glioblastoma cells.","date":"2010","source":"British journal of cancer","url":"https://pubmed.ncbi.nlm.nih.gov/20197768","citation_count":56,"is_preprint":false},{"pmid":"12595898","id":"PMC_12595898","title":"Evaluation of human leukocyte N-formylpeptide receptor (FPR1) SNPs in aggressive periodontitis patients.","date":"2003","source":"Genes and immunity","url":"https://pubmed.ncbi.nlm.nih.gov/12595898","citation_count":53,"is_preprint":false},{"pmid":"27432059","id":"PMC_27432059","title":"The role of formyl peptide receptor 1 (FPR1) in neuroblastoma tumorigenesis.","date":"2016","source":"BMC cancer","url":"https://pubmed.ncbi.nlm.nih.gov/27432059","citation_count":52,"is_preprint":false},{"pmid":"23860188","id":"PMC_23860188","title":"CCR5 and FPR1 mediate neutrophil recruitment in endotoxin-induced lung injury.","date":"2013","source":"Journal of innate immunity","url":"https://pubmed.ncbi.nlm.nih.gov/23860188","citation_count":51,"is_preprint":false},{"pmid":"9850337","id":"PMC_9850337","title":"Chemotaxins C5a and fMLP induce release of calprotectin (leucocyte L1 protein) from polymorphonuclear cells in vitro.","date":"1998","source":"Molecular pathology : MP","url":"https://pubmed.ncbi.nlm.nih.gov/9850337","citation_count":50,"is_preprint":false},{"pmid":"20599799","id":"PMC_20599799","title":"The hederagenin saponin SMG-1 is a natural FMLP receptor inhibitor that suppresses human neutrophil activation.","date":"2010","source":"Biochemical pharmacology","url":"https://pubmed.ncbi.nlm.nih.gov/20599799","citation_count":50,"is_preprint":false},{"pmid":"18812505","id":"PMC_18812505","title":"Superoxide anions regulate TORC1 and its ability to bind Fpr1:rapamycin complex.","date":"2008","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/18812505","citation_count":47,"is_preprint":false},{"pmid":"3118996","id":"PMC_3118996","title":"Platelet-leukocyte interaction: activation of rabbit platelets by FMLP-stimulated neutrophils.","date":"1987","source":"British journal of pharmacology","url":"https://pubmed.ncbi.nlm.nih.gov/3118996","citation_count":47,"is_preprint":false},{"pmid":"35112667","id":"PMC_35112667","title":"Overriding impaired FPR chemotaxis signaling in diabetic neutrophil stimulates infection control in murine diabetic wound.","date":"2022","source":"eLife","url":"https://pubmed.ncbi.nlm.nih.gov/35112667","citation_count":44,"is_preprint":false},{"pmid":"28062700","id":"PMC_28062700","title":"Intravital Imaging of Neutrophil Recruitment Reveals the Efficacy of FPR1 Blockade in Hepatic Ischemia-Reperfusion Injury.","date":"2017","source":"Journal of immunology (Baltimore, Md. : 1950)","url":"https://pubmed.ncbi.nlm.nih.gov/28062700","citation_count":44,"is_preprint":false},{"pmid":"24350845","id":"PMC_24350845","title":"Development of small molecule non-peptide formyl peptide receptor (FPR) ligands and molecular modeling of their recognition.","date":"2014","source":"Current medicinal chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/24350845","citation_count":43,"is_preprint":false},{"pmid":"3022713","id":"PMC_3022713","title":"Double stimulation with FMLP and Con A restores the activation of the respiratory burst but not of the phosphoinositide turnover in Ca2+-depleted human neutrophils. A further example of dissociation between stimulation of the NADPH oxidase and phosphoinositide turnover.","date":"1986","source":"Biochemical and biophysical research communications","url":"https://pubmed.ncbi.nlm.nih.gov/3022713","citation_count":43,"is_preprint":false},{"pmid":"33046534","id":"PMC_33046534","title":"A TLR3 Ligand Reestablishes Chemotherapeutic Responses in the Context of FPR1 Deficiency.","date":"2020","source":"Cancer discovery","url":"https://pubmed.ncbi.nlm.nih.gov/33046534","citation_count":42,"is_preprint":false},{"pmid":"17611713","id":"PMC_17611713","title":"Production of angiogenic factors by human glioblastoma cells following activation of the G-protein coupled formylpeptide receptor FPR.","date":"2007","source":"Journal of neuro-oncology","url":"https://pubmed.ncbi.nlm.nih.gov/17611713","citation_count":41,"is_preprint":false},{"pmid":"23185575","id":"PMC_23185575","title":"Regulation of the formyl peptide receptor 1 (FPR1) gene in primary human macrophages.","date":"2012","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/23185575","citation_count":40,"is_preprint":false},{"pmid":"1546853","id":"PMC_1546853","title":"FMLP causes eicosanoid-dependent vasoconstriction and edema in lungs from endotoxin-primed rats.","date":"1992","source":"The American review of respiratory disease","url":"https://pubmed.ncbi.nlm.nih.gov/1546853","citation_count":39,"is_preprint":false},{"pmid":"16568107","id":"PMC_16568107","title":"hPepT1 mediates bacterial tripeptide fMLP uptake in human monocytes.","date":"2006","source":"Laboratory investigation; a journal of technical methods and pathology","url":"https://pubmed.ncbi.nlm.nih.gov/16568107","citation_count":38,"is_preprint":false},{"pmid":"11607790","id":"PMC_11607790","title":"Contrasting evolution of the human leukocyte N-formylpeptide receptor subtypes FPR and FPRL1R.","date":"2001","source":"Genes and immunity","url":"https://pubmed.ncbi.nlm.nih.gov/11607790","citation_count":37,"is_preprint":false},{"pmid":"26378785","id":"PMC_26378785","title":"Gliadin Induces Neutrophil Migration via Engagement of the Formyl Peptide Receptor, FPR1.","date":"2015","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/26378785","citation_count":37,"is_preprint":false},{"pmid":"21372136","id":"PMC_21372136","title":"N-formyl-methionyl-leucyl-phenylalanine (fMLP) promotes osteoblast differentiation via the N-formyl peptide receptor 1-mediated signaling pathway in human mesenchymal stem cells from bone marrow.","date":"2011","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/21372136","citation_count":36,"is_preprint":false},{"pmid":"28232203","id":"PMC_28232203","title":"Dipeptide HCH6-1 inhibits neutrophil activation and protects against acute lung injury by blocking FPR1.","date":"2017","source":"Free radical biology & medicine","url":"https://pubmed.ncbi.nlm.nih.gov/28232203","citation_count":35,"is_preprint":false},{"pmid":"15951351","id":"PMC_15951351","title":"Neutrophil NADPH-oxidase activation by an annexin AI peptide is transduced by the formyl peptide receptor (FPR), whereas an inhibitory signal is generated independently of the FPR family receptors.","date":"2005","source":"Journal of leukocyte biology","url":"https://pubmed.ncbi.nlm.nih.gov/15951351","citation_count":34,"is_preprint":false},{"pmid":"16360643","id":"PMC_16360643","title":"Expression analysis of the fpr (ferredoxin-NADP+ reductase) gene in Pseudomonas putida KT2440.","date":"2006","source":"Biochemical and biophysical research communications","url":"https://pubmed.ncbi.nlm.nih.gov/16360643","citation_count":33,"is_preprint":false},{"pmid":"27144520","id":"PMC_27144520","title":"Exogenous carbon monoxide inhibits neutrophil infiltration in LPS-induced sepsis by interfering with FPR1 via p38 MAPK but not GRK2.","date":"2016","source":"Oncotarget","url":"https://pubmed.ncbi.nlm.nih.gov/27144520","citation_count":33,"is_preprint":false},{"pmid":"25201101","id":"PMC_25201101","title":"The intricate role of mast cell proteases and the annexin A1-FPR1 system in abdominal wall endometriosis.","date":"2014","source":"Journal of molecular histology","url":"https://pubmed.ncbi.nlm.nih.gov/25201101","citation_count":31,"is_preprint":false},{"pmid":"33040403","id":"PMC_33040403","title":"Functional selective FPR1 signaling in favor of an activation of the neutrophil superoxide generating NOX2 complex.","date":"2020","source":"Journal of leukocyte biology","url":"https://pubmed.ncbi.nlm.nih.gov/33040403","citation_count":31,"is_preprint":false},{"pmid":"11714831","id":"PMC_11714831","title":"The endogenous opioid spinorphin blocks fMet-Leu-Phe-induced neutrophil chemotaxis by acting as a specific antagonist at the N-formylpeptide receptor subtype FPR.","date":"2001","source":"Journal of immunology (Baltimore, Md. : 1950)","url":"https://pubmed.ncbi.nlm.nih.gov/11714831","citation_count":31,"is_preprint":false},{"pmid":"12361388","id":"PMC_12361388","title":"Cyclosporins: structure-activity relationships for the inhibition of the human FPR1 formylpeptide receptor.","date":"2002","source":"Journal of medicinal chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/12361388","citation_count":29,"is_preprint":false},{"pmid":"16972170","id":"PMC_16972170","title":"Pharmacophore model for bile acids recognition by the FPR receptor.","date":"2006","source":"Journal of computer-aided molecular design","url":"https://pubmed.ncbi.nlm.nih.gov/16972170","citation_count":28,"is_preprint":false},{"pmid":"25595528","id":"PMC_25595528","title":"TRPC1 regulates fMLP-stimulated migration and chemotaxis of neutrophil granulocytes.","date":"2015","source":"Biochimica et biophysica acta","url":"https://pubmed.ncbi.nlm.nih.gov/25595528","citation_count":28,"is_preprint":false},{"pmid":"30188748","id":"PMC_30188748","title":"Mitochondrial peptides cause proinflammatory responses in the alveolar epithelium via FPR-1, MAPKs, and AKT: a potential mechanism involved in acute lung injury.","date":"2018","source":"American journal of physiology. Lung cellular and molecular physiology","url":"https://pubmed.ncbi.nlm.nih.gov/30188748","citation_count":28,"is_preprint":false},{"pmid":"17560994","id":"PMC_17560994","title":"Phospholipase D-dependent and -independent p38MAPK activation pathways are required for superoxide production and chemotactic induction, respectively, in rat neutrophils stimulated by fMLP.","date":"2007","source":"European journal of pharmacology","url":"https://pubmed.ncbi.nlm.nih.gov/17560994","citation_count":28,"is_preprint":false},{"pmid":"8695817","id":"PMC_8695817","title":"Tumor necrosis factor-alpha and FMLP receptors are functionally linked during FMLP-stimulated activation of adherent human neutrophils.","date":"1996","source":"Blood","url":"https://pubmed.ncbi.nlm.nih.gov/8695817","citation_count":27,"is_preprint":false},{"pmid":"17481585","id":"PMC_17481585","title":"MAPKAPK2-mediated LSP1 phosphorylation and FMLP-induced neutrophil polarization.","date":"2007","source":"Biochemical and biophysical research communications","url":"https://pubmed.ncbi.nlm.nih.gov/17481585","citation_count":27,"is_preprint":false},{"pmid":"30897064","id":"PMC_30897064","title":"Elevated FPR confers to radiochemoresistance and predicts clinical efficacy and outcome of metastatic colorectal cancer patients.","date":"2019","source":"Aging","url":"https://pubmed.ncbi.nlm.nih.gov/30897064","citation_count":24,"is_preprint":false},{"pmid":"25277308","id":"PMC_25277308","title":"FPR1 interacts with CFH, HTRA1 and smoking in exudative age-related macular degeneration and polypoidal choroidal vasculopathy.","date":"2014","source":"Eye (London, England)","url":"https://pubmed.ncbi.nlm.nih.gov/25277308","citation_count":24,"is_preprint":false},{"pmid":"35712659","id":"PMC_35712659","title":"Molecular Structure, Expression and Role of TAFA4 and its Receptor FPR1 in the Spinal Cord.","date":"2022","source":"Frontiers in cell and developmental biology","url":"https://pubmed.ncbi.nlm.nih.gov/35712659","citation_count":23,"is_preprint":false},{"pmid":"19807662","id":"PMC_19807662","title":"Discovery of selective probes and antagonists for G-protein-coupled receptors FPR/FPRL1 and GPR30.","date":"2009","source":"Current topics in medicinal chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/19807662","citation_count":23,"is_preprint":false},{"pmid":"19307611","id":"PMC_19307611","title":"Absence of proteinase-activated receptor-1 signaling in mice confers protection from fMLP-induced goblet cell metaplasia.","date":"2009","source":"American journal of respiratory cell and molecular biology","url":"https://pubmed.ncbi.nlm.nih.gov/19307611","citation_count":23,"is_preprint":false},{"pmid":"11460314","id":"PMC_11460314","title":"Mechanisms and modulation of formyl-methionyl-leucyl-phenylalanine (fMLP)-induced Ca2+ mobilization in human neutrophils.","date":"2001","source":"International immunopharmacology","url":"https://pubmed.ncbi.nlm.nih.gov/11460314","citation_count":23,"is_preprint":false},{"pmid":"1331550","id":"PMC_1331550","title":"Local motor responses to bradykinin and bacterial chemotactic peptide formyl-methionyl-leucyl-phenylalanine (FMLP) in the guinea-pig isolated renal pelvis and ureter.","date":"1992","source":"The Journal of urology","url":"https://pubmed.ncbi.nlm.nih.gov/1331550","citation_count":23,"is_preprint":false},{"pmid":"2152941","id":"PMC_2152941","title":"Pertussis toxin inhibits the FMLP-induced membrane association of protein kinase C in human neutrophils.","date":"1990","source":"Journal of leukocyte biology","url":"https://pubmed.ncbi.nlm.nih.gov/2152941","citation_count":23,"is_preprint":false},{"pmid":"30419240","id":"PMC_30419240","title":"Involvement of the annexin A1-Fpr anti-inflammatory system in the ocular allergy.","date":"2018","source":"European journal of pharmacology","url":"https://pubmed.ncbi.nlm.nih.gov/30419240","citation_count":22,"is_preprint":false},{"pmid":"31401382","id":"PMC_31401382","title":"Estradiol inhibits fMLP-induced neutrophil migration and superoxide production by upregulating MKP-2 and dephosphorylating ERK.","date":"2019","source":"International immunopharmacology","url":"https://pubmed.ncbi.nlm.nih.gov/31401382","citation_count":22,"is_preprint":false},{"pmid":"35547761","id":"PMC_35547761","title":"Critical role of FPR1 in splenocyte migration into brain to worsen inflammation and ischemic brain injury in mice.","date":"2022","source":"Theranostics","url":"https://pubmed.ncbi.nlm.nih.gov/35547761","citation_count":22,"is_preprint":false},{"pmid":"24389043","id":"PMC_24389043","title":"MLK3 regulates fMLP-stimulated neutrophil motility.","date":"2014","source":"Molecular immunology","url":"https://pubmed.ncbi.nlm.nih.gov/24389043","citation_count":21,"is_preprint":false},{"pmid":"33922475","id":"PMC_33922475","title":"Formyl Peptide Receptor (FPR)1 Modulation by Resveratrol in an LPS-Induced Neuroinflammatory Animal Model.","date":"2021","source":"Nutrients","url":"https://pubmed.ncbi.nlm.nih.gov/33922475","citation_count":21,"is_preprint":false},{"pmid":"19037090","id":"PMC_19037090","title":"Regulation of the leucocyte chemoattractant receptor FPR in glioblastoma cells by cell differentiation.","date":"2008","source":"Carcinogenesis","url":"https://pubmed.ncbi.nlm.nih.gov/19037090","citation_count":21,"is_preprint":false},{"pmid":"26071379","id":"PMC_26071379","title":"A neutrophil inhibitory pepducin derived from FPR1 expected to target FPR1 signaling hijacks the closely related FPR2 instead.","date":"2015","source":"FEBS letters","url":"https://pubmed.ncbi.nlm.nih.gov/26071379","citation_count":21,"is_preprint":false},{"pmid":"38438091","id":"PMC_38438091","title":"FPR1: A critical gatekeeper of the heart and brain.","date":"2024","source":"Pharmacological research","url":"https://pubmed.ncbi.nlm.nih.gov/38438091","citation_count":20,"is_preprint":false},{"pmid":"25450672","id":"PMC_25450672","title":"Antagonism of human formyl peptide receptor 1 (FPR1) by chromones and related isoflavones.","date":"2014","source":"Biochemical pharmacology","url":"https://pubmed.ncbi.nlm.nih.gov/25450672","citation_count":20,"is_preprint":false},{"pmid":"8770090","id":"PMC_8770090","title":"C-reactive protein inhibits increased pulmonary vascular permeability induced by fMLP in isolated rabbit lungs.","date":"1996","source":"The American journal of physiology","url":"https://pubmed.ncbi.nlm.nih.gov/8770090","citation_count":20,"is_preprint":false},{"pmid":"28690139","id":"PMC_28690139","title":"4-Aroyl-3-hydroxy-5-phenyl-1H-pyrrol-2(5H)-ones as N-formyl peptide receptor 1 (FPR1) antagonists.","date":"2017","source":"Biochemical pharmacology","url":"https://pubmed.ncbi.nlm.nih.gov/28690139","citation_count":19,"is_preprint":false},{"pmid":"18207024","id":"PMC_18207024","title":"Role of different protein tyrosine kinases in fMLP-induced neutrophil transmigration.","date":"2007","source":"Immunobiology","url":"https://pubmed.ncbi.nlm.nih.gov/18207024","citation_count":19,"is_preprint":false},{"pmid":"29922854","id":"PMC_29922854","title":"fMLP-dependent activation of Akt and ERK1/2 through ROS/Rho A pathways is mediated through restricted activation of the FPRL1 (FPR2) receptor.","date":"2018","source":"Inflammation research : official journal of the European Histamine Research Society ... [et al.]","url":"https://pubmed.ncbi.nlm.nih.gov/29922854","citation_count":19,"is_preprint":false},{"pmid":"22934745","id":"PMC_22934745","title":"Role of formyl peptide receptors (FPR) in abnormal inflammation responses involved in neurodegenerative diseases.","date":"2012","source":"Anti-inflammatory & anti-allergy agents in medicinal chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/22934745","citation_count":18,"is_preprint":false},{"pmid":"17927965","id":"PMC_17927965","title":"Functional polymorphisms of the FPR1 gene and aggressive periodontitis in Japanese.","date":"2007","source":"Biochemical and biophysical research communications","url":"https://pubmed.ncbi.nlm.nih.gov/17927965","citation_count":18,"is_preprint":false},{"pmid":"32388428","id":"PMC_32388428","title":"Novel formyl peptide receptor (FPR) agonists with pyridinone and pyrimidindione scaffolds that are potentially useful for the treatment of rheumatoid arthritis.","date":"2020","source":"Bioorganic chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/32388428","citation_count":18,"is_preprint":false},{"pmid":"22383080","id":"PMC_22383080","title":"Neutrophil infiltration of the colon is independent of the FPR1 yet FPR1 deficient mice show differential susceptibilities to acute versus chronic induced colitis.","date":"2012","source":"Digestive diseases and sciences","url":"https://pubmed.ncbi.nlm.nih.gov/22383080","citation_count":18,"is_preprint":false},{"pmid":"11259567","id":"PMC_11259567","title":"Rebamipide suppresses formyl-methionyl-leucyl-phenylalanine (fMLP)-induced superoxide production by inhibiting fMLP-receptor binding in human neutrophils.","date":"2001","source":"The Journal of pharmacology and experimental therapeutics","url":"https://pubmed.ncbi.nlm.nih.gov/11259567","citation_count":18,"is_preprint":false},{"pmid":"25466613","id":"PMC_25466613","title":"IgE-dependent activation of human mast cells and fMLP-mediated activation of human eosinophils is controlled by the circadian clock.","date":"2014","source":"Molecular immunology","url":"https://pubmed.ncbi.nlm.nih.gov/25466613","citation_count":18,"is_preprint":false},{"pmid":"23189124","id":"PMC_23189124","title":"The role of water in activation mechanism of human N-formyl peptide receptor 1 (FPR1) based on molecular dynamics simulations.","date":"2012","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/23189124","citation_count":18,"is_preprint":false},{"pmid":"36817589","id":"PMC_36817589","title":"Acute-serum amyloid A and A-SAA-derived peptides as formyl peptide receptor (FPR) 2 ligands.","date":"2023","source":"Frontiers in endocrinology","url":"https://pubmed.ncbi.nlm.nih.gov/36817589","citation_count":17,"is_preprint":false},{"pmid":"39543493","id":"PMC_39543493","title":"Probiotic bacteria-released extracellular vesicles enhance macrophage phagocytosis in polymicrobial sepsis by activating the FPR1/2 pathway.","date":"2024","source":"Molecular medicine (Cambridge, Mass.)","url":"https://pubmed.ncbi.nlm.nih.gov/39543493","citation_count":17,"is_preprint":false},{"pmid":"3510127","id":"PMC_3510127","title":"The roles of HPr and FPr in the utilization of fructose by Escherichia coli.","date":"1986","source":"FEBS letters","url":"https://pubmed.ncbi.nlm.nih.gov/3510127","citation_count":17,"is_preprint":false},{"pmid":"25603955","id":"PMC_25603955","title":"(99m)Tc SPECT imaging agent based on cFLFLFK for the detection of FPR1 in inflammation.","date":"2015","source":"Dalton transactions (Cambridge, England : 2003)","url":"https://pubmed.ncbi.nlm.nih.gov/25603955","citation_count":17,"is_preprint":false},{"pmid":"17339610","id":"PMC_17339610","title":"Dissociation between the translocation and the activation of Akt in fMLP-stimulated human neutrophils--effect of prostaglandin E2.","date":"2007","source":"Journal of leukocyte biology","url":"https://pubmed.ncbi.nlm.nih.gov/17339610","citation_count":17,"is_preprint":false},{"pmid":"38710749","id":"PMC_38710749","title":"Mitigation of acute lung injury by human bronchial epithelial cell-derived extracellular vesicles via ANXA1-mediated FPR signaling.","date":"2024","source":"Communications biology","url":"https://pubmed.ncbi.nlm.nih.gov/38710749","citation_count":16,"is_preprint":false},{"pmid":"18166194","id":"PMC_18166194","title":"Changes in the ratio between FPR and FPRL1 triggered superoxide production in human neutrophils-a tool in analysing receptor specific events.","date":"2007","source":"Journal of immunological methods","url":"https://pubmed.ncbi.nlm.nih.gov/18166194","citation_count":16,"is_preprint":false},{"pmid":"23399130","id":"PMC_23399130","title":"Polysaccharides from Bupleurum chinense impact the recruitment and migration of neutrophils by blocking fMLP chemoattractant receptor-mediated functions.","date":"2012","source":"Carbohydrate polymers","url":"https://pubmed.ncbi.nlm.nih.gov/23399130","citation_count":16,"is_preprint":false},{"pmid":"8050551","id":"PMC_8050551","title":"Effects of PAF, FMLP and opsonized zymosan on the release of ECP, elastase and superoxide from human granulocytes.","date":"1994","source":"The European respiratory journal","url":"https://pubmed.ncbi.nlm.nih.gov/8050551","citation_count":16,"is_preprint":false},{"pmid":"19426837","id":"PMC_19426837","title":"The green tea polyphenol (-)-epigallocatechin-3-gallate inhibits leukocyte activation by bacterial formylpeptide through the receptor FPR.","date":"2009","source":"International immunopharmacology","url":"https://pubmed.ncbi.nlm.nih.gov/19426837","citation_count":16,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":53286,"output_tokens":7291,"usd":0.134611},"stage2":{"model":"claude-opus-4-6","input_tokens":11018,"output_tokens":3911,"usd":0.229297},"total_usd":0.363908,"stage1_batch_id":"msgbatch_0118RScg3WGaGkaZRtWZbtce","stage2_batch_id":"msgbatch_01Cpfzvtbj42aqp5oYZ5Te2s","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2009,\n      \"finding\": \"FPR1 is a seven-transmembrane, G protein-coupled receptor expressed mainly on phagocytic leukocytes that binds N-formyl peptides (including fMLF) as well as annexin 1 and its N-terminal fragments, mediating chemotaxis and activation of phagocytes; the receptor family shares significant sequence homology with FPR2/ALX and FPR3.\",\n      \"method\": \"Pharmacological characterization, radioligand binding, functional assays in transfected cells\",\n      \"journal\": \"Pharmacological reviews\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — comprehensive multi-lab pharmacological review with multiple orthogonal methods, replicated across labs\",\n      \"pmids\": [\"19498085\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"Annexin I (lipocortin I) acts as an endogenous ligand of FPR1 on human neutrophils; N-terminal peptides of annexin I bind FPR and trigger Ca2+ transients and MAP kinase signaling in a dose-dependent manner, and at lower concentrations specifically inhibit transendothelial migration and desensitize neutrophils toward chemoattractant challenge.\",\n      \"method\": \"Radioligand competition binding, Ca2+ flux assays, transendothelial migration assays, MAP kinase activation assays in primary human neutrophils\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — multiple orthogonal methods (binding, signaling, functional migration assay), foundational paper with high citations\",\n      \"pmids\": [\"10882119\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1994,\n      \"finding\": \"FMLP stimulation of FPR1 on human neutrophils activates Ras and Raf-1 kinase through a pertussis toxin-sensitive Gi2 protein, leading to MEK-1 and MAP kinase activation independently of protein kinase C, suggesting Gi2-mediated receptor signaling through the Ras/Raf/MAP kinase pathway.\",\n      \"method\": \"Immunoprecipitation kinase assays, [32P]GTP labeling of Ras, pertussis toxin inhibition, in vitro MEK phosphorylation assay\",\n      \"journal\": \"The Journal of clinical investigation\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — multiple orthogonal biochemical methods, pertussis toxin epistasis, highly cited foundational paper\",\n      \"pmids\": [\"8040337\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1997,\n      \"finding\": \"FMLP acting through FPR1 on human neutrophils activates p38 MAPK via MKK3, activates ERK (p42/44 MAPK) via pertussis toxin-sensitive G protein and MEKK1/Raf, but does not activate JNKs; p38 MAPK inhibition blocks superoxide production, adhesion, and chemotaxis downstream of FPR1.\",\n      \"method\": \"Kinase activity assays, immunoprecipitation, pertussis toxin inhibition, p38 MAPK inhibitor (SK&F 86002), functional neutrophil assays\",\n      \"journal\": \"The Journal of clinical investigation\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — multiple orthogonal methods, distinct signaling pathway dissection\",\n      \"pmids\": [\"9062356\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"In vivo, annexin 1 peptide Ac2-26 inhibits leukocyte adhesion and emigration through both FPR1 and ALXR (FPR2); in FPR1-deficient mice, Ac2-26 retains ~50% inhibitory activity blocked by the FPR antagonist Boc2, while FPR1-deficient neutrophils still express ALXR and respond to lipoxin A4 and Ac2-26 to detach adherent leukocytes.\",\n      \"method\": \"Intravital microscopy of mouse mesenteric microcirculation I/R model, FPR1-knockout mice, receptor antagonist pharmacology, RT-PCR and protein detection of ALXR\",\n      \"journal\": \"Blood\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — genetic knockout combined with pharmacological antagonism and in vivo functional readout, replicated with multiple tools\",\n      \"pmids\": [\"12560218\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"Human mitochondria-derived N-formylated hexapeptides (fMMYALF, fMLKLIV, fMFADRW) are potent agonists equally active on FPR1 and FPRL1 (EC50 ~10–160 nM), whereas Listeria monocytogenes-derived bacterial peptides are 100-fold more potent on FPR1 than FPRL1; none activate FPRL2.\",\n      \"method\": \"Fura-2 calcium mobilization assays in HL-60 cell lines stably transfected with FPR1, FPRL1, or FPRL2; chemotaxis assays\",\n      \"journal\": \"European journal of immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — quantitative receptor-specific functional assays with multiple peptides and transfected cell lines\",\n      \"pmids\": [\"16025565\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"Mitochondrial degradation products activate human neutrophils via FPR1 (not FPRL1); anti-FPR1 antibody completely blocked mitochondrial peptide-induced intracellular Ca2+ responses, and mitochondrial peptides induced FPR1-dependent chemotaxis and oxidative burst comparable to fMLF.\",\n      \"method\": \"Cytosolic Ca2+ measurements with antibody blockade of FPR1 vs FPRL1, trans-well chemotaxis assays, oxidative burst assay with carboxycarboxy-2',7'-dichlorodihydrofluorescein diacetate\",\n      \"journal\": \"The Journal of trauma\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — specific antibody blockade differentiating FPR1 vs FPRL1, multiple orthogonal functional readouts\",\n      \"pmids\": [\"20539176\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"Mouse FPR2 (encoded by Fpr-rs2) is a low-affinity N-formylpeptide receptor expressed on neutrophils; fMLF induces two distinct concentration optima for chemotaxis in normal mouse neutrophils (high- and low-affinity), but only the high-concentration optimum in FPR1-knockout neutrophils, establishing FPR1 as the high-affinity fMLF receptor mediating the lower-concentration chemotaxis response.\",\n      \"method\": \"HEK293 stable transfection, Ca2+ flux, chemotaxis assays, FPR knockout mouse neutrophils\",\n      \"journal\": \"The Journal of experimental medicine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — genetic knockout epistasis combined with transfected cell functional assays\",\n      \"pmids\": [\"10477558\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"FPR1 expressed by glioblastoma cell line U-87 mediates chemotaxis (increased motility), cell proliferation, and VEGF production in response to fMLF; FPR1 siRNA knockdown substantially reduced tumorigenicity in nude mice and revealed that necrotic glioblastoma cells release endogenous FPR1 agonists.\",\n      \"method\": \"RT-PCR, chemotaxis assay, siRNA knockdown, BrdU proliferation, xenograft nude mouse model, ELISA for VEGF\",\n      \"journal\": \"Journal of the National Cancer Institute\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — loss-of-function (siRNA) with multiple phenotypic readouts and in vivo xenograft validation\",\n      \"pmids\": [\"15928303\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Annexin A1 released by drug-stimulated PBMCs activates FPR1 on SJS/TEN keratinocytes to trigger necroptosis via RIP1-RIP3 complex formation; SJS/TEN keratinocytes specifically upregulate FPR1 expression, and inhibition of necroptosis or absence of FPR1-annexed A1 signaling prevented keratinocyte death.\",\n      \"method\": \"Mass spectrometry identification of annexin A1, antibody depletion, RIP1/RIP3 complex detection, immunostaining for FPR1, mouse SJS/TEN model with necroptosis inhibitor\",\n      \"journal\": \"Science translational medicine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — mass spectrometry identification, antibody depletion, KO model, multiple mechanistic steps validated\",\n      \"pmids\": [\"25031270\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"LcrV, the needle cap protein of Yersinia pestis type III secretion system, binds FPR1 on human immune cells to facilitate translocation of bacterial effectors; Fpr1-deficient mice show increased survival from plague infection, and the FPR1-R190W variant in humans confers resistance to Y. pestis-mediated neutrophil destruction.\",\n      \"method\": \"Protein-receptor binding studies, Fpr1-knockout mouse infection model, functional assays with FPR1-R190W variant neutrophils\",\n      \"journal\": \"Nature\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — genetic knockout in vivo model, human variant functional validation, highly cited\",\n      \"pmids\": [\"31534221\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Downstream of the fMLF-FPR1 receptor, Rac1 mediates uncapping of existing actin free barbed ends (FBE), whereas Rac2 regulates cofilin-mediated severing and ARP2/3-mediated de novo nucleation; relative contributions are uncapping 15%, cofilin severing 10%, ARP2/3 nucleation 75%.\",\n      \"method\": \"Neutrophils from Rac1- or Rac2-deficient mice, neutrophil permeabilization model maintaining receptor signaling, actin free barbed end assay\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — genetic knockout cells combined with biochemical actin dynamics assay dissecting distinct mechanisms\",\n      \"pmids\": [\"17954607\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"The endogenous opioid spinorphin acts as a specific competitive antagonist at FPR1: it induces Ca2+ flux in normal mouse neutrophils and FPR1-transfected HEK293 cells but is inactive in FPR1-knockout neutrophils and FPR2-expressing cells, and blocks fMLF-induced FPR1-selective chemotaxis without affecting FPR2-selective responses.\",\n      \"method\": \"Ca2+ flux assays, FPR1-knockout mouse neutrophils, FPR1- and FPR2-transfected HEK293 cells, chemotaxis assays\",\n      \"journal\": \"Journal of immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — gain- and loss-of-function genetics (KO + transfection) with functional assays\",\n      \"pmids\": [\"11714831\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"FPR1 is required for effective neutrophil recruitment to the damaged lung; Fpr1-/- mice are protected from bleomycin-induced pulmonary fibrosis due to failure to recruit neutrophils, and adoptive transfer shows this defect is intrinsic to fpr1-/- neutrophils rather than the lung environment.\",\n      \"method\": \"Fpr1 knockout mice, bleomycin lung fibrosis model, adoptive transfer of wild-type neutrophils into fpr1-/- mice, cell counting\",\n      \"journal\": \"JCI insight\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — knockout mouse model with adoptive transfer demonstrating cell-intrinsic mechanism\",\n      \"pmids\": [\"32102985\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"FPR1 is required in the enteric nervous system for commensal bacteria (LGG)-mediated increases in GI motility; LGG-induced myenteric ROS production, MAPK1 phosphorylation, and increased choline acetyltransferase expression are absent in FPR1-knockout mice, and require bacterial adhesion.\",\n      \"method\": \"FPR1-knockout mice, germ-free mice, gavage experiments, immunoblots, immunostaining, fluorescence in situ hybridization, ex vivo muscle contraction assays\",\n      \"journal\": \"Gastroenterology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — genetic knockout with multiple mechanistic readouts and in vivo functional consequence\",\n      \"pmids\": [\"30930024\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"For anthracycline-based chemotherapy to be immunogenic, dying cancer cells release annexin A1 (ANXA1) which interacts with FPR1 on dendritic cells; FPR1-deficient mice show deficient chemotherapeutic responses and earlier cancer development, and FPR1 loss-of-function alleles are associated with earlier cancer development in humans.\",\n      \"method\": \"FPR1-knockout mouse tumor models, dendritic cell and T-cell functional assays, ANXA1-knockout tumor models, human clinical data for FPR1 alleles\",\n      \"journal\": \"Cancer discovery\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple genetic models (FPR1-KO, ANXA1-KO) with mechanistic immune readouts\",\n      \"pmids\": [\"33046534\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"FPR1 activation by fMLF in glioblastoma cells transactivates EGFR and promotes glioma cell chemotaxis, invasion, growth, and production of angiogenic factors; this is triggered by endogenous agonist annexin A1 released by necrotic glioma cells.\",\n      \"method\": \"RT-PCR, flow cytometry, siRNA, chemotaxis assay, EGFR transactivation assays, xenograft mouse model\",\n      \"journal\": \"International immunopharmacology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 — mechanistic pathway placement (FPR1→EGFR transactivation) but primary data cited from prior work; review with limited new experimental data\",\n      \"pmids\": [\"22863814\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1994,\n      \"finding\": \"The NH2-terminal extracellular domain of FPR1 is not critical for plasma membrane transport or high-affinity N-formyl peptide binding; replacing the NH2-terminal domain of FPR1 with that of C5aR or FPRH resulted in normal cell surface expression and ligand binding, establishing that the FPR1 N-terminus is dispensable for receptor folding/transport.\",\n      \"method\": \"C5aR/FPR chimeric receptor construction, transfection into cells, radioligand binding assays, immunofluorescence for membrane localization\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — reconstitution with chimeric receptors and mutagenesis with direct functional and localization readouts\",\n      \"pmids\": [\"8106386\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1990,\n      \"finding\": \"FMLP-induced protein kinase C translocation (membrane association) and superoxide generation in human neutrophils are both dependent on a pertussis toxin-sensitive G protein, whereas PMA-, ionomycin-, or A23187-induced PKC translocation and superoxide generation are pertussis toxin-insensitive, placing FPR1 upstream of a Gi-dependent PKC activation cascade.\",\n      \"method\": \"Pertussis toxin pretreatment, subcellular fractionation for PKC activity, superoxide generation assay\",\n      \"journal\": \"Journal of leukocyte biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — pharmacological dissection with pertussis toxin; single lab, single primary method\",\n      \"pmids\": [\"2152941\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"FPR1 (not FPR2 or FPR3) is upregulated during osteoblastic differentiation of human bone marrow mesenchymal stem cells; fMLP acting through FPR1 promotes osteoblastic commitment via FPR1-PLC/PLD-Ca2+-CaMKII-ERK-CREB signaling and suppresses adipogenic commitment, with FPR1 antagonist cyclosporine H blocking these effects.\",\n      \"method\": \"qPCR, flow cytometry for FPR expression, calcium mobilization, western blot for phospho-signaling, siRNA knockdown, osteogenic/adipogenic differentiation assays, zebrafish and rabbit in vivo bone formation\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal methods defining signaling pathway, in vitro and in vivo validation\",\n      \"pmids\": [\"21372136\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"FPR1 expressed in neuroblastoma cells mediates calcium mobilization and activates MAPK/Erk, PI3K/Akt, and p38-MAPK signaling upon fMLP stimulation; FPR1 shRNA knockdown delayed xenograft tumor development, while FPR1 overexpression promoted tumorigenesis in nude mice.\",\n      \"method\": \"Calcium mobilization assay, phospho-specific western blots, shRNA knockdown, cDNA overexpression, nude mouse xenograft model\",\n      \"journal\": \"BMC cancer\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — loss- and gain-of-function with in vivo tumor model and mechanistic signaling pathway data\",\n      \"pmids\": [\"27432059\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"FPR1 mediates neutrophil recruitment to LPS-induced lung injury and jointly with CCR5 orchestrates neutrophil infiltration; Fpr1-/- mice or mice treated with FPR1 antagonist showed reduced neutrophil counts in all lung compartments, reduced edema, and reduced histological lung damage.\",\n      \"method\": \"Fpr1-knockout mice, LPS aerosol model, pharmacological FPR1 antagonist, lung compartment neutrophil counting\",\n      \"journal\": \"Journal of innate immunity\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — genetic knockout with pharmacological validation and defined cellular phenotype\",\n      \"pmids\": [\"23860188\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"The uPAR-derived SRSRY peptide stimulates cell migration and F-actin polarization via FPR1; fMLF at 100 nM inhibits SRSRY-stimulated migration, and SRSRY promotes FPR1-dependent vitronectin release and increased uPAR·αvβ5 vitronectin receptor association, with αvβ5 required for ERK1/2 phosphorylation downstream of FPR1.\",\n      \"method\": \"Chemotaxis assays with alanine-substituted SRSRY analogues, F-actin staining, competitive binding with fMLF, ERK1/2 phosphorylation, co-immunoprecipitation of uPAR and αvβ5\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 — multiple functional assays and co-IP, but signaling pathway partly inferred from inhibitor studies\",\n      \"pmids\": [\"15866865\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"The small compound RE-04-001 specifically activates FPR1 at very low concentrations (EC50 ~1 nM for NADPH-oxidase activation) and is a biased agonist that strongly activates the PLC-PIP2-Ca2+ pathway and ERK1/2 but shows minimal β-arrestin recruitment and requires higher concentrations for chemotaxis, demonstrating functional selectivity downstream of FPR1.\",\n      \"method\": \"Ca2+ flux, ROS measurement, β-arrestin recruitment assay (BRET), chemotaxis assay, receptor-specific pharmacological antagonists in human neutrophils and HL-60 cells\",\n      \"journal\": \"Journal of leukocyte biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — multiple assays showing biased signaling, single lab\",\n      \"pmids\": [\"33040403\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"Molecular dynamics simulations of FPR1 modeled on the CXCR4 template reveal that receptor activation involves a water molecule transiently bridging a hydrogen bond between W254(6.48) and N108(3.35), and a rotamer switch of Y301(7.53) facilitates movement of water molecules toward the receptor center, with agonist fMLF contacting R201(5.38) and R205(5.42) on TM5.\",\n      \"method\": \"Homology modeling using CXCR4 as template, molecular dynamics simulations of FPR1 with agonist fMLF and antagonist tBocMLF in model membrane\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 4 — computational modeling only, no experimental mutagenesis or structural validation\",\n      \"pmids\": [\"23189124\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"FPR1 is required for splenocyte migration into ischemic brain tissue; FPR1 antagonist cFLFLFK inhibited splenocyte and monocyte/neutrophil brain infiltration and neuroinflammatory cytokine production, and fpr1-/- mice showed reduced peripheral immune cell infiltration into brain with improved neurological outcomes after stroke.\",\n      \"method\": \"Fpr1-knockout mice, transient focal brain ischemia model, FPR1 antagonist cFLFLFK, in vitro and in vivo splenocyte migration assays, cytokine measurement, neurological scoring\",\n      \"journal\": \"Theranostics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — genetic knockout plus pharmacological blockade with functional brain injury readouts\",\n      \"pmids\": [\"35547761\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"Exposure to diabetic-range glucose impairs FPR chemotaxis signaling in neutrophils, leading to reduced chemotaxis and delayed neutrophil trafficking in wounds of Lepr(db/db) diabetic mice; CCL3 engagement of auxiliary receptors overrides the FPR signaling requirement and restores infection control.\",\n      \"method\": \"Human neutrophil chemotaxis assays at elevated glucose, Lepr(db/db) mouse wound infection model, CCL3 supplementation rescue experiments\",\n      \"journal\": \"eLife\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — in vitro and in vivo functional assays with genetic diabetic model and pathway rescue\",\n      \"pmids\": [\"35112667\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"FPR1 blockade by cyclosporine H (CsH) inhibits neutrophil accumulation at necrotic areas in the liver during ischemia-reperfusion injury; two-photon intravital microscopy demonstrated that FPR1 signaling regulates neutrophil chemotaxis and crawling velocity into necrotic zones while not affecting monocyte/macrophage recruitment.\",\n      \"method\": \"Two-photon laser-scanning microscopy in LysM-eGFP mice, FPR1 antagonist CsH, hepatic I/R model, serum transaminases, histology\",\n      \"journal\": \"Journal of immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — live intravital imaging with pharmacological FPR1 blockade, single lab\",\n      \"pmids\": [\"28062700\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"A pepducin derived from the third intracellular loop of FPR1 inhibits neutrophil superoxide production and granule mobilization, but acts by selectively targeting FPR2 (not FPR1 as designed); the fatty acid moiety is essential for inhibition and the compound blocks FPR2 agonist binding to neutrophil surfaces.\",\n      \"method\": \"Superoxide production assay, granule mobilization assay, receptor-specific desensitization, FPR2 agonist binding competition in human neutrophils\",\n      \"journal\": \"FEBS letters\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 — receptor selectivity determined by multiple functional assays, single lab\",\n      \"pmids\": [\"26071379\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"Exogenous CO (via CORM-2) inhibits LPS-stimulated neutrophil migration toward fMLF by internalizing FPR1 through a p38 MAPK-dependent (not GRK2-dependent) mechanism.\",\n      \"method\": \"Affymetrix gene chip array, under-agarose migration assay, western blot for FPR1 internalization and p38 MAPK/GRK2 phosphorylation, in vivo LPS sepsis mouse model\",\n      \"journal\": \"Oncotarget\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 — biochemical mechanism with functional readout, single lab\",\n      \"pmids\": [\"27144520\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"FPR1 is a seven-transmembrane Gi-coupled GPCR on phagocytic leukocytes that recognizes N-formyl peptides from bacteria and mitochondria, as well as endogenous ligands including annexin A1, and upon ligand binding activates Gi2-dependent Ras/Raf/ERK and p38 MAPK signaling cascades, Rac1/Rac2-regulated actin remodeling for chemotaxis, NADPH oxidase for superoxide production, and—in glioblastoma cells—transactivates EGFR to drive invasion and angiogenesis; FPR1 also serves as the entry receptor for Yersinia pestis type III secretion on immune cells, and its interaction with annexin A1 on dendritic cells is required for immunogenic cell death during anthracycline chemotherapy.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"FPR1 is a Gi-coupled seven-transmembrane receptor that senses N-formyl peptides from bacteria and mitochondria as well as the endogenous ligand annexin A1, functioning as a master chemotactic receptor that directs phagocyte recruitment to sites of infection, tissue damage, and sterile inflammation. Ligand binding activates pertussis toxin-sensitive Gi2 signaling through Ras/Raf/ERK and p38 MAPK cascades, PLC-mediated calcium mobilization, and Rac1/Rac2-dependent actin remodeling that together drive chemotaxis, NADPH oxidase-dependent superoxide production, and degranulation [PMID:8040337, PMID:9062356, PMID:17954607]. Beyond innate immunity, FPR1 on dendritic cells is required for immunogenic cell death signaling during anthracycline chemotherapy via annexin A1 recognition, and FPR1 serves as the entry receptor exploited by the Yersinia pestis type III secretion needle-cap protein LcrV, with Fpr1-deficient mice showing increased resistance to plague [PMID:33046534, PMID:31534221]. FPR1 is also expressed in non-immune contexts including glioblastoma and neuroblastoma cells, where it transactivates EGFR to promote tumor growth and angiogenesis, and in the enteric nervous system, where it transduces commensal bacterial signals to regulate gastrointestinal motility [PMID:15928303, PMID:30930024].\",\n  \"teleology\": [\n    {\n      \"year\": 1990,\n      \"claim\": \"The first signaling step downstream of FPR1 was placed at a pertussis toxin-sensitive G protein coupling to both PKC translocation and superoxide generation, establishing that FPR1 signals through Gi-family proteins in neutrophils.\",\n      \"evidence\": \"Pertussis toxin pretreatment of human neutrophils with subcellular PKC fractionation and superoxide assay\",\n      \"pmids\": [\"2152941\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Gi subtype not identified\", \"no direct receptor–G protein biochemistry\"]\n    },\n    {\n      \"year\": 1994,\n      \"claim\": \"The downstream MAPK cascade was delineated: FPR1 activates Ras→Raf-1→MEK-1→ERK through Gi2, independent of PKC, establishing a canonical mitogenic signaling arm for a chemoattractant receptor.\",\n      \"evidence\": \"Immunoprecipitation kinase assays, GTP-Ras pull-down, pertussis toxin epistasis in human neutrophils\",\n      \"pmids\": [\"8040337\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"how Gi2 βγ subunits activate Ras was unresolved\", \"p38 MAPK arm not yet tested\"]\n    },\n    {\n      \"year\": 1994,\n      \"claim\": \"Chimeric receptor studies showed the FPR1 N-terminal extracellular domain is dispensable for ligand binding and membrane trafficking, redirecting attention to transmembrane and extracellular loop determinants of formyl-peptide recognition.\",\n      \"evidence\": \"C5aR/FPR and FPRH/FPR chimeric receptor transfection with radioligand binding and immunofluorescence\",\n      \"pmids\": [\"8106386\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"specific ligand-contact residues in TM domains not mapped experimentally\"]\n    },\n    {\n      \"year\": 1997,\n      \"claim\": \"A parallel p38 MAPK pathway (via MKK3) was resolved as essential for FPR1-dependent superoxide, adhesion, and chemotaxis, while JNK was excluded, completing the bifurcation of FPR1 into ERK and p38 effector arms.\",\n      \"evidence\": \"Kinase assays, immunoprecipitation, and p38 inhibitor SK&F 86002 in human neutrophils\",\n      \"pmids\": [\"9062356\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"how p38 specifically controls NADPH oxidase vs. adhesion was unclear\"]\n    },\n    {\n      \"year\": 1999,\n      \"claim\": \"Knockout mouse studies proved FPR1 is the high-affinity fMLF receptor mediating low-concentration chemotactic responses, resolving pharmacological ambiguity about receptor identity in mouse neutrophils.\",\n      \"evidence\": \"Fpr1-knockout mouse neutrophils, two-optimum chemotaxis assay, HEK293 transfection\",\n      \"pmids\": [\"10477558\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"mouse Fpr gene family complexity left ligand selectivity of Fpr-rs2 incompletely defined\"]\n    },\n    {\n      \"year\": 2000,\n      \"claim\": \"Annexin A1 was identified as an endogenous FPR1 ligand that at low concentrations desensitizes neutrophils and inhibits transendothelial migration, establishing FPR1 as a receptor with dual pro- and anti-inflammatory signaling capacity depending on ligand concentration.\",\n      \"evidence\": \"Radioligand competition, Ca²⁺ flux, MAP kinase, and transendothelial migration assays in primary human neutrophils\",\n      \"pmids\": [\"10882119\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"precise structural determinants of bimodal signaling unresolved\", \"in vivo relevance of annexin A1–FPR1 axis not yet tested\"]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"In vivo validation using Fpr1-knockout mice in an ischemia-reperfusion model showed annexin A1 peptide Ac2-26 acts through both FPR1 and FPR2/ALX to inhibit leukocyte trafficking, quantifying ~50% of anti-inflammatory activity as FPR1-dependent.\",\n      \"evidence\": \"Intravital microscopy of mesenteric microcirculation in Fpr1-KO mice with pharmacological antagonists\",\n      \"pmids\": [\"12560218\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"relative contribution of FPR1 vs FPR2 varies by tissue and model\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Mitochondrial N-formyl peptides were shown to be potent FPR1 agonists comparable to bacterial peptides, establishing that FPR1 senses host-derived danger signals from mitochondrial damage, while bacterial formyl peptides showed 100-fold FPR1 selectivity over FPRL1.\",\n      \"evidence\": \"Ca²⁺ mobilization and chemotaxis in HL-60 lines stably expressing FPR1, FPRL1, or FPRL2\",\n      \"pmids\": [\"16025565\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"in vivo significance of mitochondrial DAMPs acting through FPR1 not yet demonstrated\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"FPR1 expression was discovered on glioblastoma cells where it drives tumor motility, proliferation, and VEGF production, extending FPR1 biology beyond innate immunity to cancer.\",\n      \"evidence\": \"siRNA knockdown with chemotaxis, BrdU, VEGF ELISA, and nude mouse xenograft\",\n      \"pmids\": [\"15928303\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"identity of endogenous glioma-derived FPR1 agonist not fully characterized\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"The cytoskeletal effectors downstream of FPR1 were dissected: Rac2 controls ARP2/3-dependent nucleation (~75% of actin assembly) and cofilin-mediated severing, while Rac1 regulates barbed-end uncapping, explaining how FPR1 coordinates directional actin polymerization for chemotaxis.\",\n      \"evidence\": \"Permeabilized neutrophils from Rac1- or Rac2-knockout mice with actin free barbed end assays\",\n      \"pmids\": [\"17954607\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"upstream GEFs linking Gi to Rac1 vs Rac2 activation not identified\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Antibody blockade definitively attributed mitochondrial DAMP-induced neutrophil activation (Ca²⁺, chemotaxis, oxidative burst) to FPR1 rather than FPRL1, confirming FPR1 as the primary mitochondrial danger receptor on neutrophils in trauma.\",\n      \"evidence\": \"Anti-FPR1 vs anti-FPRL1 blocking antibodies with Ca²⁺, chemotaxis, and ROS assays\",\n      \"pmids\": [\"20539176\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"specific mitochondrial peptide sequences driving in vivo sterile inflammation not mapped\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"FPR1 was found to direct mesenchymal stem cell fate: activation promotes osteoblastic over adipogenic differentiation via PLC/PLD-Ca²⁺-CaMKII-ERK-CREB signaling, revealing a non-immune developmental role.\",\n      \"evidence\": \"FPR1 expression profiling, siRNA, calcium mobilization, phospho-signaling, in vivo zebrafish and rabbit bone formation\",\n      \"pmids\": [\"21372136\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"physiological source of formyl peptides in bone marrow niche unknown\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"FPR1 was identified as the receptor through which annexin A1 triggers necroptosis in keratinocytes during Stevens-Johnson syndrome/toxic epidermal necrolysis, via RIP1-RIP3 complex formation.\",\n      \"evidence\": \"Mass spectrometry of PBMC secretome, antibody depletion, RIP1/RIP3 detection, mouse SJS/TEN model with necroptosis inhibitor\",\n      \"pmids\": [\"25031270\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"why keratinocytes upregulate FPR1 in SJS/TEN is mechanistically unexplained\", \"whether FPR1 directly activates necroptosis machinery or signals through intermediate kinases not defined\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"FPR1 was shown to function in enteric neurons, transducing commensal bacterial signals (Lactobacillus GG) into ROS production, MAPK1 phosphorylation, and increased cholinergic neurotransmission to regulate GI motility.\",\n      \"evidence\": \"Fpr1-KO and germ-free mice, gavage, immunoblots, FISH, ex vivo muscle contraction\",\n      \"pmids\": [\"30930024\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"specific bacterial formyl peptides responsible not identified\", \"mechanism of FPR1-to-ROS coupling in neurons not delineated\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"FPR1 was revealed as the host receptor exploited by Yersinia pestis LcrV for type III secretion effector delivery into immune cells; Fpr1-deficient mice resist plague and the human FPR1-R190W variant confers neutrophil resistance.\",\n      \"evidence\": \"Protein–receptor binding, Fpr1-KO mouse plague infection, human R190W variant neutrophil functional assays\",\n      \"pmids\": [\"31534221\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"structural basis of LcrV–FPR1 interaction unresolved\", \"whether other pathogens exploit FPR1 similarly not tested\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"FPR1 on dendritic cells was established as essential for immunogenic cell death during anthracycline chemotherapy: dying cancer cells release annexin A1, which activates DC FPR1 to enable antitumor immunity; FPR1 loss-of-function alleles associate with worse cancer outcomes in humans.\",\n      \"evidence\": \"FPR1-KO and ANXA1-KO tumor mouse models, DC and T-cell assays, human clinical allele data\",\n      \"pmids\": [\"33046534\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"downstream signaling in DCs linking FPR1 to antigen cross-presentation not mapped\", \"whether FPR1 allele effect extends beyond anthracycline regimens unknown\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Biased agonism at FPR1 was demonstrated: compound RE-04-001 potently activates PLC-Ca²⁺ and ERK but minimally recruits β-arrestin, showing that FPR1 signaling outputs are dissociable and ligand-dependent.\",\n      \"evidence\": \"Ca²⁺ flux, ROS, BRET β-arrestin recruitment, chemotaxis in neutrophils and HL-60 cells\",\n      \"pmids\": [\"33040403\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"structural basis for biased signaling at FPR1 unknown\", \"single compound; generalizability to other biased ligands not shown\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"High-resolution structural data for FPR1 bound to diverse ligands (formyl peptides, annexin A1, LcrV) are needed to explain ligand selectivity, biased agonism, and the pathogen exploitation mechanism, and the signaling events downstream of FPR1 on dendritic cells that link to antigen cross-presentation remain undefined.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"no experimental FPR1 structure in the timeline\", \"GEFs coupling Gi to Rac1/Rac2 not identified\", \"DC-intrinsic FPR1 signaling cascade for immunogenic cell death unknown\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0060089\", \"supporting_discovery_ids\": [0, 5, 7, 10]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [1, 4, 15]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [0, 17, 7]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [0, 2, 3, 6, 11, 13, 21]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [2, 3, 19, 20, 23]},\n      {\"term_id\": \"R-HSA-1643685\", \"supporting_discovery_ids\": [8, 10, 16, 20]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\n      \"ANXA1\",\n      \"GNAI2\",\n      \"RAC1\",\n      \"RAC2\",\n      \"EGFR\",\n      \"MAPK14\",\n      \"MAPK1\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}