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Duong T, Rasmussen NR, Reiner DJ. Insulated Switches: Dual-Function Protein RalGEF RGL-1 Promotes Developmental Fidelity. Int J Mol Sci 2020; 21:ijms21207610. [PMID: 33076222 PMCID: PMC7588897 DOI: 10.3390/ijms21207610] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Revised: 10/10/2020] [Accepted: 10/12/2020] [Indexed: 02/05/2023] Open
Abstract
The C. elegans vulva is an excellent model for the study of developmental biology and cell–cell signaling. The developmental induction of vulval precursor cells (VPCs) to assume the 3°-3°-2°-1°-2°-3° patterning of cell fates occurs with 99.8% accuracy. During C. elegans vulval development, an EGF signal from the anchor cell initiates the activation of RasLET-60 > RafLIN-45 > MEKMEK-2 > ERKMPK-1 signaling cascade to induce the 1° cell. The presumptive 1° cell signals its two neighboring cells via NotchLIN-12 to develop 2° cells. In addition, RasLET-60 switches effectors to RalGEFRGL-1 > RalRAL-1 to promote 2° fate. Shin et al. (2019) showed that RalGEFRGL-1 is a dual-function protein in VPCs fate patterning. RalGEFRGL-1 functions as a scaffold for PDKPDK-1 > AktAKT-1/2 modulatory signaling to promote 1° fate in addition to propagating the RasLET-60 modulatory signal through RalRAL-1 to promote 2° fate. The deletion of RalGEFRGL-1 increases the frequency of VPC patterning errors 15-fold compared to the wild-type control. We speculate that RalGEFRGL-1 represents an “insulated switch”, whereby the promotion of one signaling activity curtails the promotion of the opposing activity. This property might increase the impact of the switch on fidelity more than two separately encoded proteins could. Understanding how developmental fidelity is controlled will help us to better understand the origins of cancer and birth defects, which occur in part due to the misspecification of cell fates.
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Affiliation(s)
- Tam Duong
- Institute of Biosciences and Technology, Texas A&M Health Science Center, Texas A&M University, Houston, TX 77030, USA; (T.D.); (N.R.R.)
- Department of Translational Medical Science, College of Medicine, Texas A&M Health Science Center, Texas A&M University, Houston, TX 77030, USA
| | - Neal R. Rasmussen
- Institute of Biosciences and Technology, Texas A&M Health Science Center, Texas A&M University, Houston, TX 77030, USA; (T.D.); (N.R.R.)
- Department of Translational Medical Science, College of Medicine, Texas A&M Health Science Center, Texas A&M University, Houston, TX 77030, USA
| | - David J. Reiner
- Institute of Biosciences and Technology, Texas A&M Health Science Center, Texas A&M University, Houston, TX 77030, USA; (T.D.); (N.R.R.)
- Department of Translational Medical Science, College of Medicine, Texas A&M Health Science Center, Texas A&M University, Houston, TX 77030, USA
- Correspondence:
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2
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Shin H, Braendle C, Monahan KB, Kaplan REW, Zand TP, Mote FS, Peters EC, Reiner DJ. Developmental fidelity is imposed by genetically separable RalGEF activities that mediate opposing signals. PLoS Genet 2019; 15:e1008056. [PMID: 31086367 PMCID: PMC6534338 DOI: 10.1371/journal.pgen.1008056] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2018] [Revised: 05/24/2019] [Accepted: 02/28/2019] [Indexed: 02/06/2023] Open
Abstract
The six C. elegans vulval precursor cells (VPCs) are induced to form the 3°-3°-2°-1°-2°-3° pattern of cell fates with high fidelity. In response to EGF signal, the LET-60/Ras-LIN-45/Raf-MEK-2/MEK-MPK-1/ERK canonical MAP kinase cascade is necessary to induce 1° fate and synthesis of DSL ligands for the lateral Notch signal. In turn, LIN-12/Notch receptor is necessary to induce neighboring cells to become 2°. We previously showed that, in response to graded EGF signal, the modulatory LET-60/Ras-RGL-1/RalGEF-RAL-1/Ral signal promotes 2° fate in support of LIN-12. In this study, we identify two key differences between RGL-1 and RAL-1. First, deletion of RGL-1 confers no overt developmental defects, while previous studies showed RAL-1 to be essential for viability and fertility. From this observation, we hypothesize that the essential functions of RAL-1 are independent of upstream activation. Second, RGL-1 plays opposing and genetically separable roles in VPC fate patterning. RGL-1 promotes 2° fate via canonical GEF-dependent activation of RAL-1. Conversely, RGL-1 promotes 1° fate via a non-canonical GEF-independent activity. Our genetic epistasis experiments are consistent with RGL-1 functioning in the modulatory 1°-promoting AGE-1/PI3-Kinase-PDK-1-AKT-1 cascade. Additionally, animals lacking RGL-1 experience 15-fold higher rates of VPC patterning errors compared to the wild type. Yet VPC patterning in RGL-1 deletion mutants is not more sensitive to environmental perturbations. We propose that RGL-1 functions to orchestrate opposing 1°- and 2°-promoting modulatory cascades to decrease developmental stochasticity. We speculate that such switches are broadly conserved but mostly masked by paralog redundancy or essential functions. Developmental signals are increasingly conceptualized in the context of networks rather than linear pathways. Patterning of C. elegans vulval fates is mostly governed by two major signaling cascades that operate antagonistically to induce two cell identities. An additional pair of minor cascades support each of the major cascades. All components in this system are conserved in mammalian oncogenic signaling networks. We find that RGL-1, a component of one of the minor cascades, performs two antagonistic functions. Its deletion appears to abolish both opposing modulatory signals, resulting in a 15-fold increase in the basal error rate in development of these cells. We hypothesize that the bifunctional RGL-1 protein defines a novel mechanism by which signaling networks are interwoven to mitigate developmental errors.
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Affiliation(s)
- Hanna Shin
- Institute of Biosciences and Technology, Texas A&M Health Science Center, Texas A&M University, Houston, TX, United States of America
| | | | - Kimberly B Monahan
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC, United States of America
| | - Rebecca E W Kaplan
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC, United States of America
| | - Tanya P Zand
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC, United States of America.,Department of Pharmacology, University of North Carolina, Chapel Hill, NC, United States of America
| | - Francisca Sefakor Mote
- Institute of Biosciences and Technology, Texas A&M Health Science Center, Texas A&M University, Houston, TX, United States of America
| | - Eldon C Peters
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC, United States of America
| | - David J Reiner
- Institute of Biosciences and Technology, Texas A&M Health Science Center, Texas A&M University, Houston, TX, United States of America.,Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC, United States of America.,Department of Pharmacology, University of North Carolina, Chapel Hill, NC, United States of America
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3
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Sheng Y, Wei J, Zhang Y, Gao X, Wang Z, Yang J, Yan S, Zhu Y, Zhang Z, Xu D, Wang C, Zheng Y, Dong Q, Qin L. Mutated EPHA2 is a target for combating lymphatic metastasis in intrahepatic cholangiocarcinoma. Int J Cancer 2019; 144:2440-2452. [PMID: 30412282 DOI: 10.1002/ijc.31979] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2018] [Revised: 10/22/2018] [Accepted: 11/02/2018] [Indexed: 12/13/2022]
Abstract
Exploring the genetic aberrations favoring metastasis is important for understanding and developing novel strategies to combat cancer metastasis. It remains lack of effective treatment for the dismal prognosis of intrahepatic cholangiocarcinoma (ICC). Here, we aimed to study genetic alternations during lymph node metastasis of ICC and investigate potential mechanisms and clinical strategy focused on mutations. We performed whole-exome sequencing and transcriptome sequencing on samples from 30 ICC patients, including lymph node metastases from five of the patients. We identified the alterations of genetic pattern related to lymph node metastases of ICC. EPHA2, a member of the tyrosine kinase family, was found to be frequently mutated in ICC. Correlation analysis indicated that EPHA2 mutations were closely associated with lymph node metastasis of ICC. In vitro and in vivo experiments revealed that EPHA2 mutations could lead to ligand independent phosphorylation of Ser897, and promote lymphatic metastasis of ICC, in which NOTCH1 signaling pathway played an important role. In both in vitro assays and patient-derived xenografts, an inhibitor of Ser897 phosphorylation effectively suppressed the metastasis of ICC with mutated EPHA2. Our findings demonstrated that EPHA2 mutants may be an attractive therapeutic target for lymphatic metastasis of ICC.
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Affiliation(s)
- Yuanyuan Sheng
- Department of General Surgery, Huashan Hospital and Cancer Metastasis Institute and Institutes of Biomedical Sciences, Fudan University, Shanghai, China
| | - Jinwang Wei
- Department of General Surgery, Huashan Hospital and Cancer Metastasis Institute and Institutes of Biomedical Sciences, Fudan University, Shanghai, China
| | - Yu Zhang
- Department of General Surgery, Huashan Hospital and Cancer Metastasis Institute and Institutes of Biomedical Sciences, Fudan University, Shanghai, China
| | - Xiaomei Gao
- Department of General Surgery, Huashan Hospital and Cancer Metastasis Institute and Institutes of Biomedical Sciences, Fudan University, Shanghai, China
| | - Zheng Wang
- Department of General Surgery, Huashan Hospital and Cancer Metastasis Institute and Institutes of Biomedical Sciences, Fudan University, Shanghai, China
| | - Jing Yang
- Department of General Surgery, Huashan Hospital and Cancer Metastasis Institute and Institutes of Biomedical Sciences, Fudan University, Shanghai, China
| | - Shican Yan
- Department of General Surgery, Huashan Hospital and Cancer Metastasis Institute and Institutes of Biomedical Sciences, Fudan University, Shanghai, China
| | - Ying Zhu
- Department of General Surgery, Huashan Hospital and Cancer Metastasis Institute and Institutes of Biomedical Sciences, Fudan University, Shanghai, China
| | - Ze Zhang
- Department of General Surgery, Huashan Hospital and Cancer Metastasis Institute and Institutes of Biomedical Sciences, Fudan University, Shanghai, China
| | - Da Xu
- Department of General Surgery, Huashan Hospital and Cancer Metastasis Institute and Institutes of Biomedical Sciences, Fudan University, Shanghai, China
| | - Chaoqun Wang
- Department of General Surgery, Huashan Hospital and Cancer Metastasis Institute and Institutes of Biomedical Sciences, Fudan University, Shanghai, China
| | - Yan Zheng
- Department of General Surgery, Huashan Hospital and Cancer Metastasis Institute and Institutes of Biomedical Sciences, Fudan University, Shanghai, China
| | - Qiongzhu Dong
- Department of General Surgery, Huashan Hospital and Cancer Metastasis Institute and Institutes of Biomedical Sciences, Fudan University, Shanghai, China
| | - Lunxiu Qin
- Department of General Surgery, Huashan Hospital and Cancer Metastasis Institute and Institutes of Biomedical Sciences, Fudan University, Shanghai, China
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Shin H, Reiner DJ. The Signaling Network Controlling C. elegans Vulval Cell Fate Patterning. J Dev Biol 2018; 6:E30. [PMID: 30544993 PMCID: PMC6316802 DOI: 10.3390/jdb6040030] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Revised: 12/08/2018] [Accepted: 12/10/2018] [Indexed: 12/17/2022] Open
Abstract
EGF, emitted by the Anchor Cell, patterns six equipotent C. elegans vulval precursor cells to assume a precise array of three cell fates with high fidelity. A group of core and modulatory signaling cascades forms a signaling network that demonstrates plasticity during the transition from naïve to terminally differentiated cells. In this review, we summarize the history of classical developmental manipulations and molecular genetics experiments that led to our understanding of the signals governing this process, and discuss principles of signal transduction and developmental biology that have emerged from these studies.
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Affiliation(s)
- Hanna Shin
- Institute of Biosciences and Technology, Texas A&M Health Science Center, Houston, TX 77030, USA.
| | - David J Reiner
- Institute of Biosciences and Technology, Texas A&M Health Science Center, Houston, TX 77030, USA.
- College of Medicine, Texas A & M University, Houston, TX 77030, USA.
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5
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Rasmussen NR, Dickinson DJ, Reiner DJ. Ras-Dependent Cell Fate Decisions Are Reinforced by the RAP-1 Small GTPase in Caenorhabditiselegans. Genetics 2018; 210:1339-1354. [PMID: 30257933 PMCID: PMC6283165 DOI: 10.1534/genetics.118.301601] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Accepted: 09/15/2018] [Indexed: 12/15/2022] Open
Abstract
The notoriety of the small GTPase Ras as the most mutated oncoprotein has led to a well-characterized signaling network largely conserved across metazoans. Yet the role of its close relative Rap1 (Ras Proximal), which shares 100% identity between their core effector binding sequences, remains unclear. A long-standing controversy in the field is whether Rap1 also functions to activate the canonical Ras effector, the S/T kinase Raf. We used the developmentally simpler Caenorhabditis elegans, which lacks the extensive paralog redundancy of vertebrates, to examine the role of RAP-1 in two distinct LET-60/Ras-dependent cell fate patterning events: induction of 1° vulval precursor cell (VPC) fate and of the excretory duct cell. Fluorescence-tagged endogenous RAP-1 is localized to plasma membranes and is expressed ubiquitously, with even expression levels across the VPCs. RAP-1 and its activating GEF PXF-1 function cell autonomously and are necessary for maximal induction of 1° VPCs. Critically, mutationally activated endogenous RAP-1 is sufficient both to induce ectopic 1°s and duplicate excretory duct cells. Like endogenous RAP-1, before induction GFP expression from the pxf-1 promoter is uniform across VPCs. However, unlike endogenous RAP-1, after induction GFP expression is increased in presumptive 1°s and decreased in presumptive 2°s. We conclude that RAP-1 is a positive regulator that promotes Ras-dependent inductive fate decisions. We hypothesize that PXF-1 activation of RAP-1 serves as a minor parallel input into the major LET-60/Ras signal through LIN-45/Raf.
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Affiliation(s)
- Neal R Rasmussen
- Institute of Biosciences and Technology, College of Medicine, Texas A&M University, Houston, Texas 77030
| | - Daniel J Dickinson
- Department of Molecular Biosciences, University of Texas, Austin, Texas 78705
| | - David J Reiner
- Institute of Biosciences and Technology, College of Medicine, Texas A&M University, Houston, Texas 77030
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6
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Shin H, Kaplan REW, Duong T, Fakieh R, Reiner DJ. Ral Signals through a MAP4 Kinase-p38 MAP Kinase Cascade in C. elegans Cell Fate Patterning. Cell Rep 2018; 24:2669-2681.e5. [PMID: 30184501 PMCID: PMC6484852 DOI: 10.1016/j.celrep.2018.08.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Revised: 06/18/2018] [Accepted: 08/06/2018] [Indexed: 12/24/2022] Open
Abstract
C. elegans vulval precursor cell (VPC) fates are patterned by an epidermal growth factor (EGF) gradient. High-dose EGF induces 1° VPC fate, and lower dose EGF contributes to 2° fate in support of LIN-12/Notch. We previously showed that the EGF 2°-promoting signal is mediated by LET-60/Ras switching effectors, from the canonical Raf-MEK-ERK mitogen-activated protein (MAP) kinase cascade that promotes 1° fate to the non-canonical RalGEF-Ral that promotes 2° fate. Of oncogenic Ras effectors, RalGEF-Ral is by far the least well understood. We use genetic analysis to identify an effector cascade downstream of C. elegans RAL-1/Ral, starting with an established Ral binding partner, Exo84 of the exocyst complex. Additionally, RAL-1 signals through GCK-2, a citron-N-terminal-homology-domain-containing MAP4 kinase, and PMK-1/p38 MAP kinase cascade to promote 2° fate. Our study delineates a Ral-dependent developmental signaling cascade in vivo, thus providing the mechanism by which lower EGF dose is transduced.
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Affiliation(s)
- Hanna Shin
- Center for Translational Cancer Research, Institute of Biosciences and Technology, Texas A&M Health Science Center, Houston, TX 77030, USA
| | - Rebecca E W Kaplan
- Department of Pharmacology and Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, Chapel Hill, NC 27599, USA
| | - Tam Duong
- Center for Translational Cancer Research, Institute of Biosciences and Technology, Texas A&M Health Science Center, Houston, TX 77030, USA
| | - Razan Fakieh
- Center for Translational Cancer Research, Institute of Biosciences and Technology, Texas A&M Health Science Center, Houston, TX 77030, USA
| | - David J Reiner
- Center for Translational Cancer Research, Institute of Biosciences and Technology, Texas A&M Health Science Center, Houston, TX 77030, USA; Department of Medical Physiology, College of Medicine, Texas A&M University, College Station, TX 77843, USA; Department of Pharmacology and Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, Chapel Hill, NC 27599, USA.
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7
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Ping X, Tang C. An Atlas of Network Topologies Reveals Design Principles for Caenorhabditis elegans Vulval Precursor Cell Fate Patterning. PLoS One 2015; 10:e0131397. [PMID: 26114587 PMCID: PMC4482679 DOI: 10.1371/journal.pone.0131397] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2015] [Accepted: 06/01/2015] [Indexed: 12/11/2022] Open
Abstract
The vulval precursor cell (VPC) fate patterning in Caenorhabditis elegans is a classic model experimental system for cell fate determination and patterning in development. Despite its apparent simplicity (six neighboring cells arranged in one dimension) and many experimental and computational efforts, the patterning strategy and mechanism remain controversial due to incomplete knowledge of the complex biology. Here, we carry out a comprehensive computational analysis and obtain a reservoir of all possible network topologies that are capable of VPC fate patterning under the simulation of various biological environments and regulatory rules. We identify three patterning strategies: sequential induction, morphogen gradient and lateral antagonism, depending on the features of the signal secreted from the anchor cell. The strategy of lateral antagonism, which has not been reported in previous studies of VPC patterning, employs a mutual inhibition of the 2° cell fate in neighboring cells. Robust topologies are built upon minimal topologies with basic patterning strategies and have more flexible and redundant implementations of modular functions. By simulated mutation, we find that all three strategies can reproduce experimental error patterns of mutants. We show that the topology derived by mapping currently known biochemical pathways to our model matches one of our identified functional topologies. Furthermore, our robustness analysis predicts a possible missing link related to the lateral antagonism strategy. Overall, we provide a theoretical atlas of all possible functional networks in varying environments, which may guide novel discoveries of the biological interactions in vulval development of Caenorhabditis elegans and related species.
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Affiliation(s)
- Xianfeng Ping
- Center for Quantitative Biology and Peking-Tsinghua Center for Life Sciences, Peking University, Beijing, China
| | - Chao Tang
- Center for Quantitative Biology and Peking-Tsinghua Center for Life Sciences, Peking University, Beijing, China
- * E-mail:
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Gentry LR, Martin TD, Reiner DJ, Der CJ. Ral small GTPase signaling and oncogenesis: More than just 15minutes of fame. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2014; 1843:2976-2988. [PMID: 25219551 DOI: 10.1016/j.bbamcr.2014.09.004] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2014] [Revised: 09/03/2014] [Accepted: 09/04/2014] [Indexed: 01/26/2023]
Abstract
Since their discovery in 1986, Ral (Ras-like) GTPases have emerged as critical regulators of diverse cellular functions. Ral-selective guanine nucleotide exchange factors (RalGEFs) function as downstream effectors of the Ras oncoprotein, and the RalGEF-Ral signaling network comprises the third best characterized effector of Ras-dependent human oncogenesis. Because of this, Ral GTPases as well as their effectors are being explored as possible therapeutic targets in the treatment of RAS mutant cancer. The two Ral isoforms, RalA and RalB, interact with a variety of downstream effectors and have been found to play key and distinct roles in both normal and neoplastic cell physiology including regulation of vesicular trafficking, migration and invasion, tumor formation, metastasis, and gene expression. In this review we provide an overview of Ral biochemistry and biology, and we highlight recent discoveries.
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Affiliation(s)
- Leanna R Gentry
- University of North Carolina at Chapel Hill, Department of Pharmacology, Chapel Hill, NC, USA
| | | | - David J Reiner
- Institute of Biosciences and Technology, Texas A&M Health Science Center, Houston, TX, USA
| | - Channing J Der
- University of North Carolina at Chapel Hill, Department of Pharmacology, Chapel Hill, NC, USA; University of North Carolina at Chapel Hill, Lineberger Comprehensive Cancer Center, Chapel Hill, NC, USA.
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Ras. Mol Oncol 2013. [DOI: 10.1017/cbo9781139046947.022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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