Towards Combinatorial Biosynthesis of Pyrrolamide Antibiotics in Streptomyces Celine Aubry
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Chemical Science View Article Online EDGE ARTICLE View Journal | View Issue Aromatic side-chain flips orchestrate the conformational sampling of functional loops in Cite this: Chem. Sci.,2021,12,9318 † All publication charges for this article human histone deacetylase 8 have been paid for by the Royal Society a a bcd of Chemistry Vaibhav Kumar Shukla, ‡ Lucas Siemons, ‡ Francesco L. Gervasio and D. Flemming Hansen *a Human histone deacetylase 8 (HDAC8) is a key hydrolase in gene regulation and an important drug-target. High-resolution structures of HDAC8 in complex with substrates or inhibitors are available, which have provided insights into the bound state of HDAC8 and its function. Here, using long all-atom unbiased molecular dynamics simulations and Markov state modelling, we show a strong correlation between the conformation of aromatic side chains near the active site and opening and closing of the surrounding functional loops of HDAC8. We also investigated two mutants known to allosterically downregulate the enzymatic activity of HDAC8. Based on experimental data, we hypothesise that I19S-HDAC8 is unable to Received 6th April 2021 Creative Commons Attribution 3.0 Unported Licence. release the product, whereas both product release and substrate binding are impaired in the S39E- Accepted 27th May 2021 HDAC8 mutant. The presented results deliver detailed insights into the functional dynamics of HDAC8 DOI: 10.1039/d1sc01929e and provide a mechanism for the substantial downregulation caused by allosteric mutations, including rsc.li/chemical-science a disease causing one. Introduction II (HDAC-4, -5, -6, -7, -9, and HDAC10), and class III (SIRT1-7) have sequence similarity to yeast Rpd3, Hda1, and Sir2, Acetylation of lysine side chains occurs as a co-translation or respectively, whereas class IV (HDAC11) shares sequence simi- 2 This article is licensed under a post-translational modication of proteins and was rst iden- larity with both class I and II proteins. -
Computational Prediction and Character Ization of Genomic Islands: Insights Into Bacterial Pathogenicity
COMPUTATIONAL PREDICTION AND CHARACTER IZATION OF GENOMIC ISLANDS: INSIGHTS INTO BACTERIAL PATHOGENICITY by Morgan Gavel Ira Langille B.Sc. University of New Brunswick, 2004 B.CS University of New Brunswick, 2004 THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY In the Department of Molecular Biology and Biochemistry © Morgan Gavel Ira Langille 2009 SIMON FRASER UNIVERSITY Summer 2009 All rights reserved. This work may not be reproduced in whole or in part, by photocopy or other means, without permission of the author. APPROVAL Name: Morgan Gavel Ira Langille Degree: Doctor of Philosophy Title of Thesis: Computational prediction and characterization of genomic islands: insights into bacterial pathogenicity Examining Committee: Chair: Dr. Paul C.H. Li Associate Professor, Department of Chemistry ______________________________________ Dr. Fiona S.L. Brinkman Senior Supervisor Associate Professor of Molecular Biology and Biochemistry ______________________________________ Dr. David L. Baillie Supervisor Professor of Molecular Biology and Biochemistry ______________________________________ Dr. Frederic F. Pio Supervisor Assistant Professor of Molecular Biology and Biochemistry ______________________________________ Dr. Jack Chen Internal Examiner Associate Professor of Molecular Biology and Biochemistry ______________________________________ Dr. Steven Hallam External Examiner Assistant Professor of Microbiology and Immunology, University of British Columbia Date Defended/Approved: Thursday April 16, 2009 ii Declaration of Partial Copyright Licence The author, whose copyright is declared on the title page of this work, has granted to Simon Fraser University the right to lend this thesis, project or extended essay to users of the Simon Fraser University Library, and to make partial or single copies only for such users or in response to a request from the library of any other university, or other educational institution, on its own behalf or for one of its users. -
Pyoverdine Production in the Pathogen Pseudomonas Aeruginosa: a Study on Cooperative Interactions Among Individuals and Its Role for Virulence
Ludwig-Maximilans-Universtiät München Pyoverdine production in the pathogen Pseudomonas aeruginosa: a study on cooperative interactions among individuals and its role for virulence Dissertation der Fakultät für Biologie der Ludwig-Maximilians-Universität München vorgelegt von Michael Weigert aus Straubing April 2017 Gutachter: 1. Prof. Kirsten Jung 2. Prof. Kai Papenfort Tag der Abgabe: 03.04.2017 Tag der mündlichen Prüfung: 09.06.2017 I Contents ContentsII 1 PrefaceV 1.1 Eidesstattliche Erklärung/Statutory Declaration . .V 1.2 Publications and Manuscripts Originating From this Thesis . .VI 1.3 Contributions to Publications and Manuscripts Presented in this Thesis . VII 1.4 Abbreviations . .IX 1.5 Summary . 10 1.6 Zusammenfassung . 12 2 Introduction 15 2.1 Cooperation in Bacteria . 16 2.1.1 Bacterial Cooperation and the Problem of Cheating . 17 2.2 Quorum Sensing . 18 2.3 Siderophores . 19 2.3.1 The Siderophores of Pseudomonas aeruginosa ........ 19 2.3.2 Pyoverdine and Virulence . 20 2.3.3 Regulation of Pyoverdine-Expression . 22 2.4 New Approaches to Fight Multi-Drug-Resistant Pathogens . 24 2.4.1 The Problem of Antibiotic Resistance . 24 2.4.2 Anti-Virulence Treatments . 26 II 2.4.3 The Evolution of Resistance to Anti-Virulence Treatments 29 2.5 Evolution Proof Drugs . 30 2.5.1 Targeting a Secreted Virulence Factor . 31 2.5.2 Targeting a Cooperatively Shared Virulence Factor . 32 2.6 Aims of this Thesis . 32 3 Gallium-Mediated Siderophore Quenching as an Evolutionarily Ro- bust Antibacterial Treatment 35 3.1 Supporting Material . 48 4 Manipulating Virulence Factor Availability Can Have Complex Con- sequences for Infections 51 4.1 Supporting Material . -
Use of Anti-Vegf Antibody in Combination With
(19) TZZ __T (11) EP 2 752 189 B1 (12) EUROPEAN PATENT SPECIFICATION (45) Date of publication and mention (51) Int Cl.: of the grant of the patent: A61K 31/337 (2006.01) A61K 39/395 (2006.01) 26.10.2016 Bulletin 2016/43 A61P 35/04 (2006.01) A61K 31/513 (2006.01) A61K 31/675 (2006.01) A61K 31/704 (2006.01) (2006.01) (21) Application number: 13189711.8 A61K 45/06 (22) Date of filing: 20.11.2009 (54) USE OF ANTI-VEGF ANTIBODY IN COMBINATION WITH CHEMOTHERAPY FOR TREATING BREAST CANCER VERWENDUNG VON ANTI-VEGF ANTIKÖRPER IN KOMBINATION MIT CHEMOTHERAPIE ZUR BEHANDLUNG VON BRUSTKREBS UTILISATION D’ANTICORPS ANTI-VEGF COMBINÉS À LA CHIMIOTHÉRAPIE POUR LE TRAITEMENT DU CANCER DU SEIN (84) Designated Contracting States: (74) Representative: Denison, Christopher Marcus et al AT BE BG CH CY CZ DE DK EE ES FI FR GR HR Mewburn Ellis LLP HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT City Tower RO SE SI SK SM TR 40 Basinghall Street London EC2V 5DE (GB) (30) Priority: 22.11.2008 US 117102 P 13.05.2009 US 178009 P (56) References cited: 18.05.2009 US 179307 P US-A1- 2009 163 699 (43) Date of publication of application: • CAMERON ET AL: "Bevacizumab in the first-line 09.07.2014 Bulletin 2014/28 treatment of metastatic breast cancer", EUROPEAN JOURNAL OF CANCER. (60) Divisional application: SUPPLEMENT, PERGAMON, OXFORD, GB 16188246.9 LNKD- DOI:10.1016/S1359-6349(08)70289-1, vol. 6, no. -
Infant Antibiotic Exposure Search EMBASE 1. Exp Antibiotic Agent/ 2
Infant Antibiotic Exposure Search EMBASE 1. exp antibiotic agent/ 2. (Acedapsone or Alamethicin or Amdinocillin or Amdinocillin Pivoxil or Amikacin or Aminosalicylic Acid or Amoxicillin or Amoxicillin-Potassium Clavulanate Combination or Amphotericin B or Ampicillin or Anisomycin or Antimycin A or Arsphenamine or Aurodox or Azithromycin or Azlocillin or Aztreonam or Bacitracin or Bacteriocins or Bambermycins or beta-Lactams or Bongkrekic Acid or Brefeldin A or Butirosin Sulfate or Calcimycin or Candicidin or Capreomycin or Carbenicillin or Carfecillin or Cefaclor or Cefadroxil or Cefamandole or Cefatrizine or Cefazolin or Cefixime or Cefmenoxime or Cefmetazole or Cefonicid or Cefoperazone or Cefotaxime or Cefotetan or Cefotiam or Cefoxitin or Cefsulodin or Ceftazidime or Ceftizoxime or Ceftriaxone or Cefuroxime or Cephacetrile or Cephalexin or Cephaloglycin or Cephaloridine or Cephalosporins or Cephalothin or Cephamycins or Cephapirin or Cephradine or Chloramphenicol or Chlortetracycline or Ciprofloxacin or Citrinin or Clarithromycin or Clavulanic Acid or Clavulanic Acids or clindamycin or Clofazimine or Cloxacillin or Colistin or Cyclacillin or Cycloserine or Dactinomycin or Dapsone or Daptomycin or Demeclocycline or Diarylquinolines or Dibekacin or Dicloxacillin or Dihydrostreptomycin Sulfate or Diketopiperazines or Distamycins or Doxycycline or Echinomycin or Edeine or Enoxacin or Enviomycin or Erythromycin or Erythromycin Estolate or Erythromycin Ethylsuccinate or Ethambutol or Ethionamide or Filipin or Floxacillin or Fluoroquinolones -
Supplementary Table 1. All Differentially Expressed Genes from Microarray Screening Analysis
Supplementary Table 1. All differentially expressed genes from microarray screening analysis. FCa (Gal-KD Gene Symbol Gene Name p-Value versus Vector) Up-regulated genes HAPLN1 hyaluronan and proteoglycan link protein 1 10.49 0.0027085 THBS1 thrombospondin 1 9.20 0.0022192 ODC1 ornithine decarboxylase 1 6.38 0.0055776 TGM2 transglutaminase 2 4.76 0.0015627 IL7R interleukin 7 receptor 4.75 0.0017245 SERINC2 serine incorporator 2 4.51 0.0014919 ITM2C integral membrane protein 2C 4.32 0.0044644 SERPINB7 serpin peptidase inhibitor, clade B, member 7 4.18 0.0081136 tumor necrosis factor receptor superfamily, member TNFRSF10D 4.01 0.0085561 10d TAGLN transgelin 3.90 0.0099963 LRRN4 leucine rich repeat neuronal 4 3.82 0.0046513 TGFB2 transforming growth factor beta 2 3.51 0.0035017 CPA4 carboxypeptidase A4 3.43 0.0008452 EPB41L3 erythrocyte membrane protein band 4.1-like 3 3.34 0.0025309 NRG1 neuregulin 1 3.28 0.0079724 F3 coagulation factor III (thromboplastin, tissue factor) 3.27 0.0038968 POLR3G polymerase III polypeptide G 3.26 0.0070675 SEMA7A semaphorin 7A 3.20 0.0087335 NT5E 5-nucleotidase 3.17 0.0036353 CAMK2N1 calmodulin-dependent protein kinase II inhibitor 1 3.07 0.0090141 TIMP3 TIMP metallopeptidase inhibitor 3 3.03 0.0047953 SERPINE1 serpin peptidase inhibitor, clade E 2.97 0.0053652 MALL mal, T-cell differentiation protein-like 2.88 0.0078205 DDAH1 dimethylarginine dimethylaminohydrolase 1 2.86 0.0002895 WDR3 WD repeat domain 3 2.85 0.0058842 WNT5A Wnt Family Member 5A 2.81 0.0043796 GPR1 G protein-coupled receptor 1 2.81 0.0021313 -
Thiazoline-Specific Amidohydrolase Purah Is the Gatekeeper of Bottromycin Biosynthesis
\ Sikandar, A., Franz, L., Melse, O., Antes, I. and Koehnke, J. (2019) Thiazoline-specific amidohydrolase PurAH is the gatekeeper of bottromycin biosynthesis. Journal of the American Chemical Society, 141(25), pp. 9748-9752. (doi: 10.1021/jacs.8b12231) The material cannot be used for any other purpose without further permission of the publisher and is for private use only. There may be differences between this version and the published version. You are advised to consult the publisher’s version if you wish to cite from it. http://eprints.gla.ac.uk/224167/ Deposited on 16 November 2020 Enlighten – Research publications by members of the University of Glasgow http://eprints.gla.ac.uk The Thiazoline-Specific Amidohydrolase PurAH is the Gatekeeper of Bottromycin Biosynthesis Asfandyar Sikandar,†,‡ Laura Franz,†,‡ Okke Melse,§ Iris Antes,§ and Jesko Koehnke†,* †Workgroup Structural Biology of Biosynthetic Enzymes, Helmholtz Institute for Pharmaceutical Research Saarland, Helmholtz Cen- tre for Infection Research, Saarland University, Campus Geb. E8.1, 66123 Saarbrücken, Germany §Center for Integrated Protein Science Munich at the TUM School of Life Sciences, Technische Universität München, Emil-Erlen- meyer-Forum 8, 85354 Freising, Germany Supporting Information Placeholder ABSTRACT: The ribosomally synthesized and post-transla- the a/b-hydrolase BotH, successive oxidative decarboxylation of tionally modified peptide (RiPP) bottromycin A2 possesses the thiazoline to a thiazole (BotCYP) and O-methylation of an potent antimicrobial activity. Its biosynthesis involves the en- aspartate (BotOMT) complete bottromycin biosynthesis. zymatic formation of a macroamidine, a process previously Scheme 1. (a) A gene cluster highly homologous in se- suggested to require the concerted efforts of a YcaO enzyme quence and organization to those of confirmed bottromy- (PurCD) and an amidohydrolase (PurAH) in vivo. -
Multiplex De Novo Sequencing of Peptide Antibiotics
JOURNAL OF COMPUTATIONAL BIOLOGY Volume 18, Number 11, 2011 Research Articles # Mary Ann Liebert, Inc. Pp. 1371–1381 DOI: 10.1089/cmb.2011.0158 Multiplex De Novo Sequencing of Peptide Antibiotics HOSEIN MOHIMANI,1 WEI-TING LIU,2 YU-LIANG YANG,3 SUSANA P. GAUDEˆ NCIO,4 WILLIAM FENICAL,4 PIETER C. DORRESTEIN,2,3 and PAVEL A. PEVZNER5 ABSTRACT Proliferation of drug-resistant diseases raises the challenge of searching for new, more efficient antibiotics. Currently, some of the most effective antibiotics (i.e., Vancomycin and Daptomycin) are cyclic peptides produced by non-ribosomal biosynthetic pathways. The isolation and sequencing of cyclic peptide antibiotics, unlike the same activity with linear peptides, is time-consuming and error-prone. The dominant technique for sequencing cyclic peptides is nuclear magnetic resonance (NMR)–based and requires large amounts (milli- grams) of purified materials that, for most compounds, are not possible to obtain. Given these facts, there is a need for new tools to sequence cyclic non-ribosomal peptides (NRPs) using picograms of material. Since nearly all cyclic NRPs are produced along with related analogs, we develop a mass spectrometry approach for sequencing all related peptides at once (in contrast to the existing approach that analyzes individual peptides). Our results suggest that instead of attempting to isolate and NMR-sequence the most abundant com- pound, one should acquire spectra of many related compounds and sequence all of them simultaneously using tandem mass spectrometry. We illustrate applications of this approach by sequencing new variants of cyclic peptide antibiotics from Bacillus brevis, as well as sequencing a previously unknown family of cyclic NRPs produced by marine bacteria. -
Ginsenosides Synergize with Mitomycin C in Combating Human Non-Small Cell Lung Cancer by Repressing Rad51-Mediated DNA Repair
Acta Pharmacologica Sinica (2018) 39: 449–458 © 2018 CPS and SIMM All rights reserved 1671-4083/18 www.nature.com/aps Article Ginsenosides synergize with mitomycin C in combating human non-small cell lung cancer by repressing Rad51-mediated DNA repair Min ZHAO, Dan-dan WANG, Yuan CHE, Meng-qiu WU, Qing-ran LI, Chang SHAO, Yun WANG, Li-juan CAO, Guang-ji WANG*, Hai-ping HAO* State Key Laboratory of Natural Medicines, Key Lab of Drug Metabolism and Pharmacokinetics, China Pharmaceutical University, Nanjing 210009, China The use of ginseng extract as an adjuvant for cancer treatment has been reported in both animal models and clinical applications, but its molecular mechanisms have not been fully elucidated. Mitomycin C (MMC), an anticancer antibiotic used as a first- or second- line regimen in the treatment for non-small cell lung carcinoma (NSCLC), causes serious adverse reactions when used alone. Here, by using both in vitro and in vivo experiments, we provide evidence for an optimal therapy for NSCLC with total ginsenosides extract (TGS), which significantly enhanced the MMC-induced cytotoxicity against NSCLC A549 and PC-9 cells in vitro when used in combination with relatively low concentrations of MMC. A NSCLC xenograft mouse model was used to confirm thein vivo synergistic effects of the combination of TGS with MMC. Further investigation revealed that TGS could significantly reverse MMC-induced S-phase cell cycle arrest and inhibit Rad51-mediated DNA damage repair, which was evidenced by the inhibitory effects of TGS on the levels of phospho- MEK1/2, phospho-ERK1/2 and Rad51 protein and the translocation of Rad51 from the cytoplasm to the nucleus in response to MMC. -
Protective Effects of Berberis Crataegina DC. (Ranunculales: Berberidaceae) Extract on Bleomycin-Induced Toxicity in Fruit Flies (Diptera: Drosophilidae)
Revista de la Sociedad Entomológica Argentina ISSN: 0373-5680 ISSN: 1851-7471 [email protected] Sociedad Entomológica Argentina Argentina Protective effects of Berberis crataegina DC. (Ranunculales: Berberidaceae) extract on Bleomycin-induced toxicity in fruit flies (Diptera: Drosophilidae) ATICI, Tuğba; ALTUN ÇOLAK, Deniz; ERSÖZ, Çağla Protective effects of Berberis crataegina DC. (Ranunculales: Berberidaceae) extract on Bleomycin-induced toxicity in fruit flies (Diptera: Drosophilidae) Revista de la Sociedad Entomológica Argentina, vol. 77, no. 4, 2018 Sociedad Entomológica Argentina, Argentina Available in: https://www.redalyc.org/articulo.oa?id=322055706003 PDF generated from XML JATS4R by Redalyc Project academic non-profit, developed under the open access initiative Artículos Protective effects of Berberis crataegina DC. (Ranunculales: Berberidaceae) extract on Bleomycin-induced toxicity in fruit flies (Diptera: Drosophilidae) Efectos protectores de extracto de Berberis crataegina DC. (Ranunculales: Berberidaceae) frente a toxicidad inducida con Bleomicina en moscas de la fruta (Diptera: Drosophilidae) Tuğba ATICI Institute of Natural and Applied Science, Erzincan Binali Yıldırım University, Turquía Deniz ALTUN ÇOLAK [email protected] Faculty of Art and Science, Erzincan Binali Yıldırım University, Turquía Çağla ERSÖZ Revista de la Sociedad Entomológica Institute of Natural and Applied Science, Erzincan Binali Yıldırım Argentina, vol. 77, no. 4, 2018 University, Turquía Sociedad Entomológica Argentina, Argentina Received: 02 October 2018 Accepted: 06 December 2018 Published: 27 December 2018 Abstract: Antineoplastic agents due to their cytotoxic effects increase the amount of free radical in cells causing cell death. e aims of this study were to assess the possible Redalyc: https://www.redalyc.org/ toxic effects of Bleomycin (BLM) on the number of offspring and survival rate of fruit articulo.oa?id=322055706003 flies as well as the protective role of Berberis crataegina DC. -
Biochemical Characterization and Comparison of Aspartylglucosaminidases Secreted in Venom of the Parasitoid Wasps Asobara Tabida and Leptopilina Heterotoma
RESEARCH ARTICLE Biochemical characterization and comparison of aspartylglucosaminidases secreted in venom of the parasitoid wasps Asobara tabida and Leptopilina heterotoma Quentin Coulette1, SeÂverine Lemauf2, Dominique Colinet2, Geneviève PreÂvost1, Caroline Anselme1, Marylène Poirie 2, Jean-Luc Gatti2* a1111111111 1 Unite ªEcologie et Dynamique des Systèmes AnthropiseÂsº (EDYSAN, FRE 3498 CNRS-UPJV), Universite de Picardie Jules Verne, Amiens, France, 2 Universite CoÃte d'Azur, INRA, CNRS, ISA, Sophia Antipolis, a1111111111 France a1111111111 a1111111111 * [email protected] a1111111111 Abstract Aspartylglucosaminidase (AGA) is a low-abundance intracellular enzyme that plays a key OPEN ACCESS role in the last stage of glycoproteins degradation, and whose deficiency leads to human Citation: Coulette Q, Lemauf S, Colinet D, PreÂvost aspartylglucosaminuria, a lysosomal storage disease. Surprisingly, high amounts of AGA- G, Anselme C, Poirie M, et al. (2017) Biochemical characterization and comparison of like proteins are secreted in the venom of two phylogenetically distant hymenopteran para- aspartylglucosaminidases secreted in venom of the sitoid wasp species, Asobara tabida (Braconidae) and Leptopilina heterotoma (Cynipidae). parasitoid wasps Asobara tabida and Leptopilina These venom AGAs have a similar domain organization as mammalian AGAs. They share heterotoma. PLoS ONE 12(7): e0181940. https:// with them key residues for autocatalysis and activity, and the mature - and -subunits also doi.org/10.1371/journal.pone.0181940 α β form an (αβ)2 structure in solution. Interestingly, only one of these AGAs subunits (α for Editor: Erjun Ling, Institute of Plant Physiology and AtAGA and for LhAGA) is glycosylated instead of the two subunits for lysosomal human Ecology Shanghai Institutes for Biological β Sciences, CHINA AGA (hAGA), and these glycosylations are partially resistant to PGNase F treatment. -
The Role of Drug Transport in Resistance to Nitrogen Mustard and Other Alkylating Agents in L5178Y Lymphoblasts1
[CANCER RESEARCH 35.1687 1692, July 1975] The Role of Drug Transport in Resistance to Nitrogen Mustard and Other Alkylating Agents in L5178Y Lymphoblasts1 Gerald J. Goldenberg2 Department of Medicine. University of Manitoba, and the Manitoba Institute of Cell Biology. Winnipeg. Manitoba. R3E OV9, Canada SUMMARY (19, 20) in normal and leukemic human lymphoid cells (25) and in rat Walker 256 carcinosarcoma cells in vitro (18). An investigation was undertaken of the mechanism of Choline, a close structural analog of HN2, has been resistance to nitrogen mustard (HN2) and other alkylating identified as the native substrate for the HN2 transport agents, with particular emphasis on the interaction between system (19). Other alkylating agents, including chlorambu cross-resistance and drug transport mechanisms in LSI78Y cil, melphalan, and intact and enzyme-activated cyclophos lymphohlasts. Dose-survival curves demonstrated that the DOfor HN2-sensitive cells (L5178Y) treated with HN2 in phamide, did not inhibit HN2 transport, suggesting inde vitro was 9.79 ng/ml and the D0 for HN2-resistant cells pendent transport mechanisms for these agents (20). Unlike HN2 transport, a study of cyclophosphamide uptake by (L5178Y/HN2) was 181.11 ng/ml; thus, sensitive cells were 18.5-fold more responsive than were resistant cells and the LSI78Y lymphoblasts demonstrated biphasic kinetics and was mediated by a facilitated diffusion mechanism (15). In difference was highly significant (p < 0.001). A similar common with HN2 transport, uptake of cyclophosphamide evaluation of 5 additional alkylating agents, including chlorambucil, melphalan, l,3-bis(2-chloroethyl)-l-nitro- was not blocked by other alkylating agents such as HN2, sourea, Mitomycin C, and 2,3,5-tris(ethyleneimino)-l,4- chlorambucil, melphalan and isophosphamide, providing additional evidence that these drugs are transported by benzoquinone, revealed that L5178Y/HN2 cells were also cross-resistant, in part, to each of these compounds.