Recent publications


  1. Braun, K., Stürzel, C.M., Biskupek, J., Kaiser, U., Kirchhoff, F., and Lindén, M. (2018). Comparison of different cytotoxicity assays for in vitro evaluation of mesoporous silica nanoparticles. Toxicol in Vitro 52, 214-221.
  2. Frich, C.K., Krüger, F., Walther, R., Domar, C., Andersen, A.H.F., Tvilum, A., Dagnæs-Hansen, F., Denton, P.W., Tolstrup, M., Paludan, S.R., Münch, J., and Zelikin, A.N. (2019). Non-covalent hitchhiking on endogenous carriers as a protraction mechanism for antiviral macromolecular prodrugs. J Control Release 294, 298-310.
  3. Krüger, F., Kumar, V., Monge, P., Conzelmann, C., Smith, N., Gothelf, K.V., Tolstrup, M., Münch, J., and Zelikin, A.N. (2019). Nucleic Acids as a Nature-Inspired Scaffold for Macromolecular Prodrugs of Nucleoside Analogues. Advanced Science 6, 1802095.
  4. Langer, S., Hammer, C., Hopfensperger, K., Klein, L., Hotter, D., De Jesus, P.D., Herbert, K.M., Pache, L., Smith, N., van der Merwe, Johannes A., et al. (2019). HIV-1 Vpu is a potent transcriptional suppressor of NF-κB-elicited antiviral immune responses. Elife 8
  5. Lippold, S., Braun, B., Krüger, F., Harms, M., Müller, J.A., Groß, R., Münch, J., and von Einem, J. (2019). Natural Inhibitor of Human Cytomegalovirus in Human Seminal Plasma. J. Virol. 93,
  6. Romero‐Molina, S., Ruiz‐Blanco, Y.B., Harms, M., Münch, J., and Sanchez‐Garcia, E. (2019). PPI‐Detect: A support vector machine model for sequence‐based prediction of protein–protein interactions. Journal of Computational Chemistry 40, 1233-1242.
  7. Sauter, D., and Kirchhoff, F. (2019). Key Viral Adaptations Preceding the AIDS Pandemic. Cell Host Microbe, 25, 27-38.


  1. Bosso, M., Ständker, L., Kirchhoff, F., and Münch, J. (2018). Exploiting the human peptidome for novel antimicrobial and anticancer agents. Bioorg. Med. Chem. 26, 2719-2726.
  2. Braun, K., Stürzel, C.M., Biskupek, J., Kaiser, U., Kirchhoff, F., and Lindén, M. (2018). Comparison of different cytotoxicity assays for in vitro evaluation of mesoporous silica nanoparticles. Toxicol in Vitro 52, 214-221.
  3. Frascaroli, G., Lecher, C., Varani, S., Setz, C., van der Merwe, J., Brune, W., and Mertens, T. (2018). Human Macrophages Escape Inhibition of Major Histocompatibility Complex-Dependent Antigen Presentation by Cytomegalovirus and Drive Proliferation and Activation of Memory CD4+ and CD8+ T Cells. Front Immunol 9, 1129.
  4. Heusinger, E., Deppe, K., Sette, P., Krapp, C., Kmiec, D., Kluge, S.F., Marx, P.A., Apetrei, C., Kirchhoff, F., and Sauter, D. (2018). Preadaptation of SIVsmm facilitated Env-mediated counteraction of human tetherin by HIV-2. J. Virol. 00276.
  5. Hotter, D., and Kirchhoff, F. (2018). Interferons and beyond: Induction of antiretroviral restriction factors. J. Leukoc. Biol. 103, 465-477.
  6. Joas, S., Parrish, E.H., Gnanadurai, C.W., Lump, E., Stürzel, C.,M., Parrish, N.F., Learn, G.H., Sauermann, U., Neumann, B., and Rensing, K.M. (2018). Species-specific host factors rather than virus-intrinsic virulence determine primate lentiviral pathogenicity. Nature Communications 9, 1371.
  7. Lodermeyer, V., Ssebyatika, G., Passos, V., Ponnurangam, A., Malassa, A., Ewald, E., Stürzel, C.,M., Kirchhoff, F., Rotger, M., and Falk, C.S. (2018). The Antiviral Activity of the Cellular Glycoprotein LGALS3BP/90K is Species-Specific. J. Virol. 00226.
  8. Mathé, P., Egah, D.Z., Müller, J.A., Shehu, N.Y., Obishakin, E.T., Shwe, D.D., Pam, V.C., Okolo, M.O., Yilgwan, C., Gomerep, S.S., et al. (2018). Low Zika virus seroprevalence among pregnant women in North Central Nigeria, 2016. Journal of Clinical Virology 105, 35-40.
  9. Morris, K.L., Buffalo, C.Z., Stürzel, C.M., Heusinger, E., Kirchhoff, F., Ren, X., and Hurley, J.H. (2018). HIV-1 Nefs Are Cargo-Sensitive AP-1 Trimerization Switches in Tetherin Downregulation. Cell 174, 671.e14.
  10. Müller, J.,A., Glöckle, A., Gawanbacht, A., Geyer, M., Münch, J., and Kirchhoff, F. (2018). Reduced Susceptibility to VIRIP-based HIV-1 Entry Inhibitors has a High Genetic Barrier and Severe Fitness Costs. J. Virol. 00733.
  11. Palesch, D., Bosinger, S.E., Tharp, G.K., Vanderford, T.H., Paiardini, M., Chahroudi, A., Johnson, Z.P., Kirchhoff, F., Hahn, B.H., and Norgren, R.B. (2018). Sooty mangabey genome sequence provides insight into AIDS resistance in a natural SIV host. Nature 553, 77.
  12. Richard, J., Prévost, J., Baxter, A.E., von Bredow, B., Ding, S., Medjahed, H., Delgado, G.G., Brassard, N., Stürzel, C.,M., and Kirchhoff, F. (2018). Uninfected Bystander Cells Impact the Measurement of HIV-Specific Antibody-Dependent Cellular Cytotoxicity Responses. mBio 9, 358.
  13. Röcker, A.E., Müller, J.A., Dietzel, E., Harms, M., Krüger, F., Heid, C., Sowislok, A., Riber, C.F., Kupke, A., Lippold, S., et al. (2018). The molecular tweezer CLR01 inhibits Ebola and Zika virus infection. Antiviral Research 152, 26-35.
  14. Röcker, A., R. Roan, N., Kant Yadav, J., Fändrich, M., and Münch, J. (2011). Structure, function and antagonism of semen amyloids. Chemical Communications (Cambridge, England) 48, 19-22.
  15. Sauter, D., and Kirchhoff, F. (2018). Multilayered and versatile inhibition of cellular antiviral factors by HIV and SIV accessory proteins. Cytokine Growth Factor Rev.
  16. Yamada, E., Nakaoka, S., Klein, L., Reith, E., Langer, S., Hopfensperger, K., Iwami, S., Schreiber, G., Kirchhoff, F., and Koyanagi, Y. (2018). Human-Specific Adaptations in Vpu Conferring Anti-tetherin Activity Are Critical for Efficient Early HIV-1 Replication In Vivo. Cell Host & Microbe 23, 110-120.


  1. Bosso, M., Ständker, L., Kirchhoff, F., and Münch, J. (2017). Exploiting the human peptidome for novel antimicrobial and anticancer agents. Bioorg. Med. Chem.
  2. Darcis, G., Van Driessche, B., Bouchat, S., Kirchhoff, F., and Van Lint, C. (2017). Molecular Control of HIV and SIV Latency. Curr. Top. Microbiol. Immunol.
  3. Guidi, N., Sacma, M., Ständker, L., Soller, K., Marka, G., Eiwen, K., Weiss, J.M., Kirchhoff, F., Weil, T., Cancelas, J.A., Florian, M.C., and Geiger, H. (2017). Osteopontin attenuates aging-associated phenotypes of hematopoietic stem cells. Embo j. 36, 840-853.
  4. Heusinger, E., and Kirchhoff, F. (2017). Primate Lentiviruses Modulate NF-kappaB Activity by Multiple Mechanisms to Fine-Tune Viral and Cellular Gene Expression. Front. Microbiol. 8, 198.
  5. Hotter, D., Krabbe, T., Reith, E., Gawanbacht, A., Rahm, N., Ayouba, A., Van Driessche, B., Van Lint, C., Peeters, M., Kirchhoff, F., and Sauter, D. (2017). Primate lentiviruses use at least three alternative strategies to suppress NF-kappaB-mediated immune activation. PLoS Pathog. 13, e1006598.
  6. Hotter, D., Sauter, D., and Kirchhoff, F. (2017). Guanylate binding protein 5: Impairing virion infectivity by targeting retroviral envelope glycoproteins. Small GTPases 8, 31-37.
  7. Jonsson, K.L., Laustsen, A., Krapp, C., Skipper, K.A., Thavachelvam, K., Hotter, D., Egedal, J.H., Kjolby, M., Mohammadi, P., Prabakaran, T., et al. (2017). IFI16 is required for DNA sensing in human macrophages by promoting production and function of cGAMP. Nat. Commun. 8, 14391.
  8. Körner, C., Simoneau, C.R., Schommers, P., Granoff, M., Ziegler, M., Holzemer, A., Lunemann, S., Chukwukelu, J., Corleis, B., Naranbhai, V., et al. (2017). HIV-1-Mediated Downmodulation of HLA-C Impacts Target Cell Recognition and Antiviral Activity of NK Cells. Cell. Host Microbe 22, 111-119.e4.
  9. Mack, K., Starz, K., Sauter, D., Langer, S., Bibollet-Ruche, F., Learn, G.H., Sturzel, C.M., Leoz, M., Plantier, J.C., Geyer, M., Hahn, B.H., and Kirchhoff, F. (2017). Efficient Vpu-Mediated Tetherin Antagonism by an HIV-1 Group O Strain. J. Virol. 91, 10.1128/JVI.02177-16. Print 2017 Mar 15.
  10. Manrique, S., Sauter, D., Horenkamp, F.A., Lulf, S., Yu, H., Hotter, D., Anand, K., Kirchhoff, F., and Geyer, M. (2017). Endocytic sorting motif interactions involved in Nef-mediated downmodulation of CD4 and CD3. Nat. Commun. 8, 442-017-00481-z.
  11. Müller, J.A., Harms, M., Schubert, A., Mayer, B., Jansen, S., Herbeuval, J.P., Michel, D., Mertens, T., Vapalahti, O., Schmidt-Chanasit, J., and Münch, J. (2017). Development of a high-throughput colorimetric Zika virus infection assay. Med. Microbiol. Immunol. 206, 175-185.
  12. Mwimanzi, F., Toyoda, M., Mahiti, M., Mann, J.K., Martin, J.N., Bangsberg, D., Brockman, M.A., Goulder, P., Kirchhoff, F., Brumme, Z.L., Ndung'u, T., and Ueno, T. (2017). Relative resistance of MHC-B to Nef-mediated downregulation is conserved among primate lentiviruses and influences antiviral T cell responses in HIV-1-infected individuals. J. Virol.
  13. Richard, J., Prevost, J., von Bredow, B., Ding, S., Brassard, N., Medjahed, H., Coutu, M., Melillo, B., Bibollet-Ruche, F., Hahn, B.H., et al. (2017). BST-2 Expression Modulates Small CD4-Mimetic Sensitization of HIV-1-Infected Cells to Antibody-Dependent Cellular Cytotoxicity. J. Virol. 91, 10.1128/JVI.00219-17. Print 2017 Jun 1.
  14. Riegger, A., Chen, C., Zirafi, O., Daiss, N., Mukherji, D., Walter, K., Tokura, Y., Stöckle, B., Kremer, K., Kirchhoff, F., et al. (2017). Synthesis of Peptide-Functionalized Poly(bis-sulfone) Copolymers Regulating HIV-1 Entry and Cancer Stem Cell Migration. ACS Macro Lett. 6, 241-246.
  15. Roan, N.R., Sandi-Monroy, N., Kohgadai, N., Usmani, S.M., Hamil, K.G., Neidleman, J., Montano, M., Ständker, L., Röcker, A., Cavrois, M., et al. (2017). Semen amyloids participate in spermatozoa selection and clearance. Elife 6, 10.7554/eLife.24888.
  16. Rode, S., Hayn, M., Röcker, A., Sieste, S., Lamla, M., Markx, D., Meier, C., Kirchhoff, F., Walther, P., Fändrich, M., Weil, T., and Münch, J. (2017). Generation and Characterization of Virus-Enhancing Peptide Nanofibrils Functionalized with Fluorescent Labels. Bioconjug. Chem. 28, 1260-1270.
  17. Schandock, F., Riber, C.F., Rocker, A., Müller, J.A., Harms, M., Gajda, P., Zuwala, K., Andersen, A.H.F., Lovschall, K.B., Tolstrup, M., et al. (2017). Macromolecular Antiviral Agents against Zika, Ebola, SARS, and Other Pathogenic Viruses. Adv. Healthc. Mater. 6, 10.1002/adhm.201700748. Epub 2017 Sep 25.
  18. Smith, N., Pietrancosta, N., Davidson, S., Dutrieux, J., Chauveau, L., Cutolo, P., Dy, M., Scott-Algara, D., Manoury, B., Zirafi, O., et al. (2017). Natural amines inhibit activation of human plasmacytoid dendritic cells through CXCR4 engagement. Nat. Commun. 8, 14253.


  1. Bego, M.G., Cong, L., Mack, K., Kirchhoff, F., and Cohen, É.A. (2016). Differential Control of BST2 Restriction and Plasmacytoid Dendritic Cell Antiviral Response by Antagonists Encoded by HIV-1 Group M and O Strains. J Virol. 90, 10236-10246.
  2. Bergman, P., Roan, N.R., Römling, U., Bevins, C.L., and Münch, J. (2016). Amyloid formation: functional friend or fearful foe? J Intern Med. 280, 139-152.
  3. Camus, C., Matusali, G., Bourry, O., Mahe, D., Aubry, F., Bujan, L., Pasquier, C., Massip, P., Ravel, C., and Zirafi, O., et al. (2016). Comparison of the effect of semen from HIV-infected and uninfected men on CD4+ T-cell infection. AIDS. 30, 1197-1208.
  4. Guidi, N., Sacma, M., Standker, L., Soller, K., Marka, G., Weiss, J., Kirchhoff, F., Weil, T., Cancelas, J., and Florian, M.C., et al. (2016). OSTEOPONTIN REGULATES AND ATTENUATES AGING-ASSOCIATED PHENOTYPES OF HSCS. Exp Hematol. 44 1, S51-S51.
  5. Heigele, A., Kmiec, D., Regensburger, K., Langer, S., Peiffer, L., Stürzel, C.M., Sauter, D., Peeters, M., Pizzato, M., and Learn, G.H., et al. (2016). The Potency of Nef-Mediated SERINC5 Antagonism Correlates with the Prevalence of Primate Lentiviruses in the Wild. Cell Host Microbe. 20, 381-391.
  6. Hotter, D., Sauter, D., and Kirchhoff, F. (2016). Guanylate binding protein 5: Impairing virion infectivity by targeting retroviral envelope glycoproteins. Small GTPases., 1-7.
  7. Klippert, A., Bleyer, M., Sauermann, U., Neumann, B., Kaul, A., Daskalaki, M., Stolte-Leeb, N., Kirchhoff, F., and Stahl-Hennig, C. (2016). Lymphocryptovirus-dependent occurrence of lymphoma in SIV-infected rhesus macaques with particular consideration to two uncommon cases of non-Hodgkin's lymphoma. Primate Biol . 3, 65-75.
  8. Kmiec, D., Iyer, S.S., Stürzel, C.M., Sauter, D., Hahn, B.H., and Kirchhoff, F. (2016). Vpu-Mediated Counteraction of Tetherin Is a Major Determinant of HIV-1 Interferon Resistance. MBio. 7.
  9. Krapp, C., Hotter, D., Gawanbacht, A., McLaren, P.J., Kluge, S.F., Stürzel, C.M., Mack, K., Reith, E., Engelhart, S., and Ciuffi, A., et al. (2016). Guanylate Binding Protein (GBP) 5 Is an Interferon-Inducible Inhibitor of HIV-1 Infectivity. Cell Host Microbe. 19, 504-514.
  10. Lavender, K.J., Gibbert, K., Peterson, K.E., van Dis, E., Francois, S., Woods, T., Messer, R.J., Gawanbacht, A., Müller, J.A., and Münch, J., et al. (2016). Interferon Alpha Subtype-Specific Suppression of HIV-1 Infection In Vivo. J Virol. 90, 6001-6013.
  11. Müller, J.A., Harms, M., Schubert, A., Jansen, S., Michel, D., Mertens, T., Schmidt-Chanasit, J., and Münch, J. (2016). Inactivation and Environmental Stability of Zika Virus. Emerg Infect Dis. 22, 1685-1687.
  12. Müller, J.A., Zirafi, O., Roan, N.R., Lee, S.J., and Münch, J. (2016). Evaluation of EPI-X4 as a urinary peptide biomarker for diagnosis and prognosis of late acute GvHD. Bone Marrow Transplant. 51, 1137-1139.
  13. Palesch, D., Boldt, F., Müller, J.A., Eisele, K., Stürzel, C.M., Wu, Y., Münch, J., and Weil, T. (2016). PEGylated Cationic Serum Albumin for Boosting Retroviral Gene Transfer. Chembiochem. 17, 1504-1508.
  14. Palesch, D., Wagner, J., Meid, A., Molenda, N., Sienczyk, M., Burkhardt, J., Münch, J., Prokop, L., Stevanovic, S., and Westhoff, M.A., et al. (2016). Cathepsin G-mediated proteolytic degradation of MHC class I molecules to facilitate immune detection of human glioblastoma cells. Cancer Immunol Immunother. 65, 283-291.
  15. Portilho, D.M., Fernandez, J., Ringeard, M., Machado, A.K., Boulay, A., Mayer, M., Müller-Trutwin, M., Beignon, A.S., Kirchhoff, F., and Nisole, S., et al. (2016). Endogenous TRIM5? Function Is Regulated by SUMOylation and Nuclear Sequestration for Efficient Innate Sensing in Dendritic Cells. Cell Rep. 14, 355-369.
  16. Röcker, A., Kirchhoff, F., and Munch, J. (2016). Combating HIV: what the human peptidome offers. Future Virol. 11, 167-170.
  17. Sauter, D., and Kirchhoff, F. (2016). HIV replication: a game of hide and sense. Curr Opin HIV AIDS. 11, 173-181.
  18. Sauter, D., and Kirchhoff, F. (2016). IFITMs: Important Factors In Trans-Mission of HIV-1. Cell Host Microbe. 20, 407-408.
  19. Vermeire, J., Roesch, F., Sauter, D., Rua, R., Hotter, D., van Nuffel, A., Vanderstraeten, H., Naessens, E., Iannucci, V., and Landi, A., et al. (2016). HIV Triggers a cGAS-Dependent, Vpu- and Vpr-Regulated Type I Interferon Response in CD4(+) T Cells. Cell Rep. 17, 413-424.
  20. Zirafi, O., Hermann, P.C., and Münch, J. (2016). Proteolytic processing of human serum albumin generates EPI-X4, an endogenous antagonist of CXCR4. J Leukoc Biol. 99, 863-868.


  1. Bächle, S.M., Sauter, D., Sibitz, S., Sandberg, J.K., Kirchhoff, F., and Moll, M. (2015). Involvement of a C-terminal motif in the interference of primate lentiviral Vpu proteins with CD1d-mediated antigen presentation. Sci Rep. 5, 9675.
  2. Buske, C., Kirchhoff, F., and Münch, J. (2015). EPI-X4, a novel endogenous antagonist of CXCR4. Oncotarget. 6, 35137-35138.
  3. Chen, J., Tibroni, N., Sauter, D., Galaski, J., Miura, T., Alter, G., Mueller, B., Haller, C., Walker, B.D., and Kirchhoff, F., et al. (2015). Modest attenuation of HIV-1 Vpu alleles derived from elite controller plasma. PLoS ONE. 10, e0120434.
  4. Ding, S., Veillette, M., Coutu, M., Prévost, J., Scharf, L., Bjorkman, P.J., Ferrari, G., Robinson, J.E., Stürzel, C., and Hahn, B.H., et al. (2015). A Highly Conserved Residue of the HIV-1 gp120 Inner Domain Is Important for Antibody-Dependent Cellular Cytotoxicity Responses Mediated by Anti-cluster A Antibodies. J Virol. 90, 2127-2134.
  5. Groß, A., Rödel, K., Kneidl, B., Donhauser, N., Mössl, M., Lump, E., Münch, J., Schmidt, B., and Eichler, J. (2015). Enhancement and induction of HIV-1 infection through an assembled peptide derived from the CD4 binding site of gp120. Chembiochem. 16, 446-454.
  6. Heigele, A., Joas, S., Regensburger, K., and Kirchhoff, F. (2015). Increased susceptibility of CD4+ T cells from elderly individuals to HIV-1 infection and apoptosis is associated with reduced CD4 and enhanced CXCR4 and FAS surface expression levels. Retrovirology. 12, 86.
  7. Heusinger, E., Kluge, S.F., Kirchhoff, F., and Sauter, D. (2015). Early Vertebrate Evolution of the Host Restriction Factor Tetherin. J Virol. 89, 12154-12165.
  8. Kaltenmeier, C., Gawanbacht, A., Beyer, T., Lindner, S., Trzaska, T., van der Merwe, J.A., Härter, G., Grüner, B., Fabricius, D., and Lotfi, R., et al. (2015). CD4+ T cell-derived IL-21 and deprivation of CD40 signaling favor the in vivo development of granzyme B-expressing regulatory B cells in HIV patients. J Immunol. 194, 3768-3777.
  9. Klippert, A., Stolte-Leeb, N., Neumann, B., Sauermann, U., Daskalaki, M., Gawanbacht, A., Kirchhoff, F., and Stahl-Hennig, C. (2015). Frequencies of lymphoid T-follicular helper cells obtained longitudinally by lymph node fine-needle aspiration correlate significantly with viral load in SIV-infected rhesus monkeys. J Med Primatol. 44, 253-262.
  10. Kluge, S.F., Sauter, D., and Kirchhoff, F. (2015). SnapShot: Antiviral Restriction Factors. Cell. 163, 774-774.e1.
  11. Langer, S.M., Hopfensperger, K., Iyer, S.S., Kreider, E.F., Learn, G.H., Lee, L.H., Hahn, B.H., and Sauter, D. (2015). A Naturally Occurring rev1-vpu Fusion Gene Does Not Confer a Fitness Advantage to HIV-1. PLoS ONE. 10, e0142118.
  12. Lump, E., Castellano, L.M., Meier, C., Seeliger, J., Erwin, N., Sperlich, B., Stürzel, C.M., Usmani, S., Hammond, R.M., and Einem, J. von, et al. (2015). A molecular tweezer antagonizes seminal amyloids and HIV infection. eLife. 4.
  13. McLaren, P.J., Gawanbacht, A., Pyndiah, N., Krapp, C., Hotter, D., Kluge, S.F., Götz, N., Heilmann, J., Mack, K., and Sauter, D., et al. (2015). Identification of potential HIV restriction factors by combining evolutionary genomic signatures with functional analyses. Retrovirology. 12, 41.
  14. Mlcochova, P., Apolonia, L., Kluge, S.F., Sridharan, A., Kirchhoff, F., Malim, M.H., Sauter, D., and Gupta, R.K. (2015). Immune evasion activities of accessory proteins Vpu, Nef and Vif are conserved in acute and chronic HIV-1 infection. Virology. 482, 72-78.
  15. Mohr, K.B., Zirafi, O., Hennies, M., Wiese, S., Kirchhoff, F., and Münch, J. (2015). Sandwich enzyme-linked immunosorbent assay for the quantification of human serum albumin fragment 408-423 in bodily fluids. Anal Biochem. 476, 29-35.
  16. Roan, N.R., and Münch, J. (2015). Improving preclinical models of HIV microbicide efficacy. Trends Microbiol. 23, 445-447.
  17. Sauter, D., Hotter, D., van Driessche, B., Stürzel, C.M., Kluge, S.F., Wildum, S., Yu, H., Baumann, B., Wirth, T., and Plantier, J.C., et al. (2015). Differential Regulation of NF-κB-Mediated Proviral and Antiviral Host Gene Expression by Primate Lentiviral Nef and Vpu Proteins. Cell Rep. 10, 586-599.
  18. Yu, H., Khalid, M., Heigele, A., Schmökel, J., M Usmani, S., van der Merwe, J., Münch, J., Silvestri, G., and Kirchhoff, F. (2015). Lentiviral nef proteins manipulate T cells in a subset-specific manner. J Virol. 89, 1986-2001.
  19. Zirafi, O., Kim, K.A., Ständker, L., Mohr, K.B., Sauter, D., Heigele, A., Kluge, S.F., Wiercinska, E., Chudziak, D., and Richter, R., et al. (2015). Discovery and characterization of an endogenous CXCR4 antagonist. Cell Rep. 11, 737-747.