Julio A. Camarero, PhD
Faculty Directory

Julio A. CamareroPhD

Julio A. CamareroPhD

Professor in Pharmacology and Pharmaceutical Sciences

Department of Pharmacology and Pharmaceutical Sciences

Julio A. Camarero started his studies in chemistry at the University of Barcelona (Spain), received his Master of Science degree in 1992, and finished his PhD thesis there in 1996. Afterward, he joined the group of Prof. Tom W. Muir at Rockefeller University as a Burroughs Wellcome Fellow, where he contributed to the development of new chemoselective ligation techniques for the chemical engineering of proteins. In 2000, he moved to the Lawrence Livermore National Laboratory as a Distinguished Lawrence Fellow, becoming a senior scientist and head of the Protein Chemistry and Engineering Laboratory in 2003. He joined the University of Southern California in 2008 as an Associate Professor.

His current research interests are focused on the development of new chemical biology approaches using protein splicing and synthetic protein chemistry to study biological processes involved in cancer and bacterial pathogenicity and how they can be modulated or inhibited by small Cys-knotted microproteins called cyclotides. Camarero has authored over 120 peer-reviewed publications and four invited book chapters. His lab is strongly funded by federal (NIH, DoD-CMDRP) and private foundation (American Cancer Society, Melanoma Research Alliance, American Lung Association) sponsors.

Dr. Camarero is a prominent researcher known for his work in protein engineering, chemical biology, and peptide/protein chemistry. One of his notable contributions is in the field of cyclotides, which are small, cyclic peptides with remarkable stability and diverse biological activities. Cyclotides are small, disulfide-rich peptides that have a stable cyclic backbone, making them highly resistant to enzymatic degradation. They have potential applications in drug design and development due to their stability and ability to bind to specific targets for the development of targeted therapies. Dr. Camarero’s work has significantly advanced the understanding and application of cyclotides, making them a promising area of research in peptide-based drug discovery.

Key Contributions of Dr. Camarero to Cyclotide Research:
1. Chemical Synthesis of Cyclotides:
• Camarero has developed methods for the chemical synthesis of cyclotides, enabling the production of these peptides in the lab. This includes using native chemical ligation (NCL) and other peptide synthesis techniques to create cyclotides with specific modifications.

2. Engineering Cyclotides for Drug Design:
• His work has focused on modifying cyclotides to enhance their therapeutic potential. Cyclotides have been engineered to target specific proteins or pathways, making them promising candidates for drug development. This includes modifying cyclotides to improve their therapeutic potential against cancer  and infectious diseases.

3. Understanding Cyclotide Folding and Stability:
• Dr. Camarero has studied the unique structural features of cyclotides, such as their cyclic backbone and disulfide bonds, which contribute to their exceptional stability. This research has provided insights into how cyclotides can be used in biomedical applications.

4. Applications in Biotechnology and Medicine:
• His research has explored the use of cyclotides in various applications, including as antimicrobial agents (specifically against multidrug-resistant bacterial pathogens), anticancer-targeted therapeutics (CXCR4, p53, and RAS/RAF pathways), and drug delivery systems primarily to access the Central Nervous System (CNS).

Areas of Expertise

  • Inteins
  • Bio-organic Chemistry
  • Biological Therapeutics
  • Microbial Pathogenicity
  • Protein and Peptide Therapeutics
  • Chemical Biology
  • Cancer
  • Genetically-encoded Biosensors
  • Drug Discovery
  • Cyclotides
  • Education

    University of Barcelona

    PhD

    University of Barcelona

    MSc

    University of Barcelona

    BSc

    The Rockefeller University

    Postdoc in Synthetic Protein Chemistry

    Lawrence Livermore National Laboratory

    Lawrence Fellow

  • Links
  • Selected Articles

    Rapid screening of cyclotide-based libraries for the selection of potent E3 ligase antagonists

    Cancer Research
    Julio A Camarero

    2019 We report novel methods for the biosynthesis of natively-folded MCoTI-based cyclotides inside live E. coli cells using a split protein splicing unit. The cyclotide MCoTI-cylotides are potent trypsin inhibitors recently isolated from the seeds of Momordica cochinchinensis, a plant member of cucurbitaceae family. Biosynthesis of genetically encoded cyclotide-based libraries opens the possibility of using single cells as microfactories where the biosynthesis and screening of a particular inhibitor can take place in a single process within the same cellular cytoplasm. The cyclotide scaffold has a tremendous potential for the development of therapeutic leads based on their extraordinary stability and potential for grafting applications. We will show an example, where a large cyclotide-based genetically-encoded library was used to screen for low nanomolar antagonists for the Hdm2-HdmX RING-mediated E3 ligase activity. We will also present different strategies to improve the cellular uptake and pharmacokinetic profiles of bioactive cyclotides.

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    The Potential of the Cyclotide Scaffold for Drug Development

    Biomedicines
    Julio A Camarero, Maria Jose Campbell

    2019 Cyclotides are a novel class of micro-proteins (≈30–40 residues long) with a unique topology containing a head-to-tail cyclized backbone structure further stabilized by three disulfide bonds that form a cystine knot. This unique molecular framework makes them exceptionally stable to physical, chemical, and biological degradation compared to linear peptides of similar size. The cyclotides are also highly tolerant to sequence variability, aside from the conserved residues forming the cystine knot, and are orally bioavailable and able to cross cellular membranes to modulate intracellular protein–protein interactions (PPIs), both in vitro and in vivo. These unique properties make them ideal scaffolds for many biotechnological applications, including drug discovery. This review provides an overview of the properties of cyclotides and their potential for the development of novel peptide-based therapeutics. The selective disruption of PPIs still remains a very challenging task, as the interacting surfaces are relatively large and flat. The use of the cell-permeable highly constrained polypeptide molecular frameworks, such as the cyclotide scaffold, has shown great promise, as it provides unique pharmacological properties. The use of molecular techniques, such as epitope grafting, and molecular evolution have shown to be highly effective for the selection of bioactive cyclotides. However, despite successes in employing cyclotides to target PPIs, some of the challenges to move them into the clinic still remain.

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    Biotechnological Applications of Protein Splicing

    Current Protein and Peptide Science
    Corina Sarmiento, Julio A Camarero

    2019 Protein splicing domains, also called inteins, have become a powerful biotechnological tool for applications involving molecular biology and protein engineering. Early applications of inteins focused on self-cleaving affinity tags, generation of recombinant polypeptide α-thioesters for the production of semisynthetic proteins and backbone cyclized polypeptides. The discovery of naturallyoccurring split-inteins has allowed the development of novel approaches for the selective modification of proteins both in vitro and in vivo. This review gives a general introduction to protein splicing with a focus on their role in expanding the applications of intein-based technologies in protein engineering and chemical biology.

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    Ribosomally synthesized and post-translationally modified peptide natural products: overview and recommendations for a universal nomenclature

    Natural Product Reports
    Paul G Arnison et al.

    2013 Covering: 1988 to 2012 This review presents recommended nomenclature for the biosynthesis of ribosomally synthesized and post-translationally modified peptides (RiPPs), a rapidly growing class of natural products. The current knowledge regarding the biosynthesis of the >20 distinct compound classes is also reviewed, and commonalities are discussed.

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    Recent developments in the site‐specific immobilization of proteins onto solid supports

    Peptide Science
    Julio A Camarero

    2008 Immobilization of proteins onto surfaces is of great importance in numerous applications, including protein analysis, drug screening, and medical diagnostics, among others. The success of all these technologies relies on the immobilization technique employed to attach a protein to the corresponding surface. Non‐specific physical adsorption or chemical cross‐linking with appropriate surfaces results in the immobilization of the protein in random orientations. Site‐specific covalent attachment, on the other hand, leads to molecules being arranged in a definite, orderly fashion and allows the use of spacers and linkers to help minimize steric hindrances between the protein and the surface. The present work reviews the latest chemical and biochemical developments for the site‐specific covalent attachment of proteins onto solid supports.

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  • Accomplishments

    Big Idea Award

    Recipient of one of the first NIH “big idea” transformative awards designed to “encourage projects so original that they have the potential to challenge fundamental beliefs,” Dr. Camarero was recognized for his research to develop a new generation of antibody substitutes.

  • Patents

    Proteolitically Resistant Cyclotides With Angiotensin 1–7 Like Activity

    US10988522B2 | 2021

    Described herein is a novel cyclotide able to activate the unique receptor of angiotensin-(1-7) (AT1-7), the MAS1 receptor. This cyclotide may be used in the treatment of cancer and myocardial infarction.

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    Synthetic apolipoproteins, and related compositions methods and systems for nanolipoprotein particles formation

    US11279749B2 | 2022

    Synthetic apolipoproteins based on native/naturally occurring homolog proteins can be prepared using solid-phase peptide synthesis approaches combined with native chemical ligation methods to create analogs of full length apolipoproteins. The chemical synthesis is expected to allow introduction of non-natural amino acids, e.g., α,α′-dialkyl amino acids, with a periodicity that encourages both helix formation and amphipathicity. Such apolipoprotein analogs are expected to encourage, in some embodiments, facile and more complete NLP formation, enabling consideration of full spectrum of nanoparticle-based biotechnology applications ranging from therapeutic sequestration and delivery to energy/biofuel production to biopolymer production.

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    Photoswitchable method for the ordered attachment of proteins to surfaces

    US7972827B2 | 2011

    Described herein is a method for the attachment of proteins to any solid support with control over the orientation of the attachment. The method is extremely efficient, not requiring the previous purification of the protein to be attached, and can be activated by UV-light. Spatially addressable arrays of multiple protein components can be generated by using standard photolithographic techniques.

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    Photoswitchable method for the ordered attachment of proteins to surface

    US7700334B2 | 2010

    Described herein is a method for the attachment of proteins to any solid support with control over the orientation of the attachment. The method is extremely efficient, not requiring the previous purification of the protein to be attached, and can be activated by UV-light. Spatially addressable arrays of multiple protein components can be generated by using standard photolithographic techniques.

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    Synthesis of peptide α-thioesters

    US7414106B2 | 2008

    Disclosed herein is a new method for the solid phase peptide synthesis (SPPS) of C-terminal peptide α thioesters using Fmoc/t-Bu chemistry. This method is based on the use of an aryl hydrazine linker, which is totally stable to conditions required for Fmoc-SPPS. When the peptide synthesis has been completed, activation of the linker is achieved by mild oxidation. The oxidation step converts the acyl-hydrazine group into a highly reactive acyl-diazene intermediate which reacts with an α-amino acid alkylthioester (H-AA-SR) to yield the corresponding peptide α-thioester in good yield. A variety of peptide thioesters, cyclic peptides and a fully functional Src homology 3 (SH3) protein domain have been successfully prepared.

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    Engineered cyclotides with potent broad antimicrobial activity

    US20240092846A1 | 2024

    Disclosed herein are novel engineered cyclotides with effective broad-spectrum antibacterial activity against several ESKAPE bacterial strains and clinical isolates.

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    Potent anti-cancer cyclotides

    WO2023215032A3 | 2024

    Provided herein are cyclotides and compositions containing the cyclotides and their use for the treatment of cancer.

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    Cyclotide-based polypeptides for therapeutic targeting of BAFF receptors in SLE

    WO2020006298A3 | 2020

    This disclosure provides a high-throughput method for identifying and isolating a candidate BAFF receptor antagonist and methods for their use in vitro and in vivo.

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    Cyclotide-based CXCR4 antagonists with anti-HIV activity

    WO2014046732A1 | 2014

    Disclosed is an isolated peptide comprising a CXCR4 antagonist peptide grafted to a cyclotide. Also described are compositions and methods for treating cancer and HIV infections using the isolated peptides.

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    Preparation of cyclotides

    WO2014046731A1 | 2014

    Provided are compositions and methods for preparing a cyclotide, in particular a cyclotide with one or more unnatural amino acids. Also provided is a polypeptide comprising a linear cyclotide fused to a C-terminal fragment and an N-terminal fragment of a split intein, at the N-terminus and C-terminus of the cyclotide, respectively. Methods of establishing screening libraries of cyclotides and use of the library for identifying pharmaceutical, therapeutic or cosmetic agents are also provided.

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    Novel cyclotides with anticancer activity

    WO2013162760A1 | 2013

    Compositions and methods are disclosed for treating a disease or condition related to p53 misregulation or dysfunction. The compositions utilize a p53 cyclotide that inhibits p53 dysregulation or inhibition.

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    Compositions and methods for the rapid biosynthesis and in vivo screening of biologically relevant peptides

    WO2011005598A1 | 2011

    This invention provides new combinatorial approaches for the biosynthesis and screening of cyclic peptides inside living cells. These novel approaches are useful for finding biologically relevant molecules, e.g., those able to inhibit the cytotoxicity of Anthrax Edema Factor. Key to this 'living combinatorial' approach is the use of a living cell as a micro-chemical factory for both synthesis and screening of potential inhibitors for a given molecular recognition event.

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  • Research Grants

    Using the Ultrastable Cyclotide Scaffold to Modulate Protein-protein Interactions

    NIH/NGMS, 20190501

    Title: Using the Ultrastable Cyclotide Scaffold to Modulate Protein-Protein Interactions. Grant # R35GM132072.

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    Therapeutic Targeting of the Hdm2/HdmX E3 Ligase in Colorectal Cancer

    American Cancer Society (ACS) Discovery Boost Award, 20240101

    Therapeutic Targeting of the Hdm2/HdmX E3 Ligase in Colorectal Cancer Grant #DBG-23-1157230-01-ET

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    Therapeutic targeting of Hdm2/HdmX E3 ligase in melanoma

    MRA Established Investigator Award, 20230601

    Therapeutic targeting of Hdm2/HdmX E3 ligase in melanoma. MRA Established Investigator Award: #1040591

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    Therapeutic Targeting of Hdm2/HdmX E3 Ligase in Lung Carcinoma

    American Lung Association (ALA), 20220701

    Treatment of lung carcinoma remains a great clinical challenge, and one candidate of interest is a novel type of compounds called cyclotides (MCo-52-2-based cyclotides). We plan to test cyclotides on several human lung carcinoma cell lines with different p53 phenotypes (null, mutated, and wild type), testing its efficacy on animal models of lung carcinoma; and to continue the development of this cyclotide selecting compounds based on cyclotide MCo-52-2 with improved activity. This will be accomplished by using the power of molecular evolution using cyclotide MCo-52-2 as template. Cyclotides with potent in vitro Hdm2/HdmX inhibitory properties will be further tested in vivo using several mouse models of lung carcinoma. We anticipate that this novel type of cyclotide-based inhibitor will have a broad spectrum of antitumor activity in human lung carcinoma cell lines both in vitro and in vivo. This could lead to the next generation of therapy of this type of cancer.

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    Therapeutic Targeting of Hdm2/HdmX E3 Ligase in metastatic CRC

    The Ming Hsieh Institute (MHI) for Research on Engineering Medicine for Cancer, 20230830

    The interaction between the RING domains of Hdm2/HdmX E3 ligase is an effective therapeutic target for cancer treatment and prevention. We have already developed a bioactive cyclotide, MCo-52-2, able to inactivate Hdm2/HdmX E3 ligase activity in vitro and in vivo. The main goal of this proposal is to continue the development of this cyclotide as a single compound therapeutic agent using several mouse models of CRC.

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    Therapeutic Targeting of Hdm2/HdmX E3 ligase in Colorectal Carcinoma

    Rosalie and Harold Rae Brown Center for Cancer Development (CCDD) Program, 20220701

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    Screening and selection of specific protein-protein antagonists using ultrastable microprotein scaffolds

    NIH/NGMS, 20150801

    Title: Screening and selection of specific protein-protein antagonists using ultrastable microprotein scaffolds. Grant # R01GM113636

    Therapeutic selective targeting of BAFF receptors

    Lupus Research Institute (LRI), 20150115

    The loss of B cell tolerance to self-antigens can lead to the production of pathogenic autoantibodies that characterize autoimmune diseases, such as systemic lupus erythematosus (SLE). In healthy individuals, competition for a limited supply of the survival factor BAFF plays a key role in the elimination of autoreactive B cells. In SLE patients, BAFF levels are elevated, which lead to increased numbers of peripheral self-reactive B cells, heightened B cell activation, and autoantibody production. Despite compelling evidence for a substantial contributory role for BAFF to SLE pathogenesis, belimumab, a human IgG1? mAb that binds and neutralizes soluble BAFF, offers only a modest clinical benefit at best. Understanding how excess BAFF promotes SLE pathology is complicated by the fact that three distinct receptors bind BAFF: BR3 (also called BAFF-R), BCMA, and TACI. BR3 mediates survival and maturation of immature B cells, whereas BCMA promotes plasma cell survival. TACI is essential for central B cell tolerance and acts as a negative regulator of the B cell compartment. Here we propose to develop selective antagonists directed against the BR3 receptor and the BCMA receptor. By eliminating BAFF signaling coupled to the survival of B cells (BR3-mediated) and plasma cells (BCMA-mediated) while sparing TACI signaling necessary for central B cell tolerance, we will selectively inhibit the disease-promoting aspects of BAFF signaling.

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    Development of Novel PD1/PD-L1 Antagonists Using Circular Cys-Knotted Micro Proteins

    Congressionally Directed Medical Research Programs (CMDRP)-Lung Cancer Research Program (LCRP), 20160401

    During these two years we have also accomplished the design and expression of a FRET-based reporter to screen antagonists for the PD-1PD-L1 complex. We have constructed and screened genetically-encoded libraries using the loops1 and 6 of cyclotide MCoTI-I. This library was screened and a bioactive cyclotide, MCo-101B, was selected. This cyclotide was able to inhibit the PD-1PD-L1 with an IC50 value of 0.66 micronM. This exciting finding represents the first cyclotide selected by molecular evolution that can inhibit the PD-1PD-L1 complex with sub-micronM activity. This cyclotide has been used to perform preliminary toxicology studies, not showing toxicity in mice with dosing up 10 mgkg. The cyclotide is being tested for efficacy in vivo in a lung cancer syngeneic model in mice.

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    Therapeutic targeting of integrin a4b7 in ulcerative colitis using ultrastable microproteins.

    Broad Medical Research Program, Crohn’s & Colitis Foundation of America, 20161001

    Grant # 483566

    Cell-based screening and selection of cyclotide-based capture reagents for protein profiling using micro-array format. Grant #: R01GM090323

    NIH/NGMS, 20090901

    Title: Cell-based screening and selection of cyclotide-based capture reagents for protein profiling using micro-array format. Grant #: R01GM090323

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    Screening and Selection of New Antagonists for the RING-Mediated Hdm2/Hdmx Interaction

    Congressionally Directed Medical Research Programs (CMDRP)-Lung Cancer Research Program (PCRP), 20100401

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    Design and development of cyclotides with new biological activities

    Bristol-Myers Squibb, 20121001

  • Multimedia
    • Dr. Camarero joined the USC School of Pharmacy in October 2008
    • Julio A. Camarero, PhD gave an invited talk,
    • Julio A. Camarero, PhD
    • Julio A. Camarero, PhD
  • Selected Media Appearances

    Researcher paves the way for new cancer treatments

    USC News | 08/20/2015

    USC Alfred E. Mann School of Pharmacy and Pharmaceutical Sciences Associate Professor Julio Camarero is getting support for his studies. The research funded by a four-year, $1.3 million RO1 grant from the National Institutes of Health focuses on the screening and selection of a novel class of protein-based therapeutics, also known as cyclotides.

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    Dr Julio Camarero was awarded a Lung Cancer Discovery Research Grant from the American Lung Association

    USC Norris Comprehensive Cancer Center | 03/12/2022

    Congratulations to USC Norris members Drs. Julio Camarero and Ite Offringa who were awarded a Lung Cancer Discovery Research Grant from the American Lung Association to study the therapeutic targeting of a novel type of cyclotide-based inhibitor in lung carcinoma.

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    Camarero Awarded $375K Melanoma Research Grant

    USC News | 05/22/2023

    Julio A. Camarero, John A. Biles Professor in Pharmaceutical Sciences at the USC Mann School of Pharmacy and Pharmaceutical Sciences, was recently awarded a three-year $375,000 grant from the Melanoma Research Alliance (MRA) for the project “Therapeutic Targeting of Hdm2/HdmX E3 Ligase in Melanoma.” The MRA Established Investigator Award is intended to support pre-clinical, translational, and early clinical research with the potential to produce unusually high-impact, near-term advancements in melanoma prevention, detection, diagnosis, and treatment, according to the Melanoma Research Alliance.

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    Camarero Receives 2023 Ming Hsieh Institute Research Award

    USC News | 09/22/2023

    Two faculty members of the USC Mann School received the 2023 Ming Hsieh Institute Research Award in support of multidisciplinary, collaborative research that accelerates the development of cancer diagnostics and treatments. Julio Camarero, John A. Biles Professor in Pharmaceutical Sciences, was awarded for his project “Therapeutic Targeting of Hdm2/HdmX E3 Ligase in CRC.”

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    Camarero Receives American Cancer Society Grant

    USC News | 10/25/2023

    Julio A. Camarero, John A. Biles Professor in Pharmaceutical Sciences at the USC Mann School of Pharmacy and Pharmaceutical Sciences, was awarded a $300,000 Discovery Boost Grant from the American Cancer Society for the project “Therapeutic Targeting of Hdm2/HdmX E3 Ligase in Colorectal Cancer.”

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    Congratulations to Drs. Julio Camarero and Heinz-Josef Lenz who received a $300,000 grant from the American Cancer Society to develop novel therapeutic agents

    USC Norris Comprehensive Cancer Center | 11/23/2023

    Congratulations to Drs. Julio Camarero and Heinz-Josef Lenz who received a $300,000 grant from the American Cancer Society to develop novel therapeutic agents for #colorectalcancer treatment. Their research project will focus on the therapeutic targeting of the Hdm2/HdmX E3 ligase in colorectal cancer. USC Alfred E. Mann School of Pharmacy and Pharmaceutical Sciences Keck School of Medicine of USC

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