TRANSFAC 2.0
Explore TRANSFAC packages
Discover
TF binding sites in promoters
and enhancers of your genes
Reconstruct
signal transduction network
controlling your genes
signal transduction network
controlling your genes

Identify
drug targets
and disease biomarkers
drug targets
and disease biomarkers

Discover
TF binding sites in promoters
and enhancers of your genes
Reconstruct
signal transduction network
controlling your genes
Identify
drug targets
and disease biomarkers
drug targets
and disease biomarkers

Discover
TF binding sites in promoters
and enhancers of your genes
Reconstruct
signal transduction network
controlling your genes
Identify
drug targets
and disease biomarkers
TRANSFAC PATHWAYS
Reconstruct signal transduction network controlling your genes
Introduction
TRANSFAC PATHWAYS package comprises everything of TRANSFAC BASIC package plus TRANSPATH®, the database of mammalian signal transduction and metabolic pathways.
With more than 1,200,000 reactions, TRANSPATH has grown into one of the largest pathway databases and is used for pathway analysis, as well as for geneXplain’s proprietary Upstream Analysis, in connection with TRANSFAC promoter analysis.
Database content
(incl. all data of TRANSFAC BASIC)TRANSPATH organizes the information about genes/molecules and reactions according to multiple hierarchies. Its sophisticated structure makes it one of the scientifically best conceptualized pathway resources, suitable for multi-purpose uses. It is complemented by one of the richest corpora of pathway data available manually curated by experts.
Reaction hierarchy in the TRANSPATH® database on molecular pathways:.

Individual reactions are documented with all experimental details, in a strictly mechanistic way that includes all reaction partners and the taxonomic origin of each molecule as reported in the published experiment (“molecular evidence level”). All evidence for a certain pathway step is accumulated to provide a more comprehensive and complete picture (“pathway step level”). On top, a semantic view is provided, which focuses on the key components only and omits mechanistic details as well as small abundant molecules (“semantic projection”). Complete networks and pathways are built from molecules and their reactions.
To consider the heterogeneity of information given in the original publications, TRANSPATH transparently but precisely differentiates protein molecules according to:
their relatedness within one genome
Information can be specifically retrieved regarding:
(a) specific individual proteins,
(b) all products of a certain gene (isoforms),
(c) different family relation levels (e.g., paralogs);
their relatedness between different genomes (orthology)
their association and modification status
(a) protein complexes are specified with their exact composition;
(b) post-translational modifications are given with their exact positions in the protein.
Pathways:
TRANSPATH® database collects and systematize canonical signal transduction and metabolic pathways. Currently it collects over 1500 various pathways.
Reaction network:
TRANSPATH® database is one of the most comprehensive repositories of signal transduction reactions in mammalian cells. It collects over 1,200,000 experimentally proven reactions of phosphorylation, acetylation, ubiquitination, translocation and other types of reactions involved in signal transduction. These reactions build a highly connected regulatory reference network which is used for analysis and reconstruction of molecular mechanisms of diseases, identification of master-regulators and drug targets.
Tools
(incl. all tools of TRANSFAC BASIC)The collected signal transduction networks can be used by the included tools for pathway analysis, particularly, in connection with TF-DNA binding motifs, this allows upstream analysis as integrated promoter-network analysis, whereby the TFs of in step 1 predicted TFBSs are used as starting point for finding master regulators in step 2 converging upstream of the transcription factors.

Pathways analysis
What is Pathway Analysis?
Most commonly, it is of interest to know which signaling or metabolic pathways are activated under certain experimental conditions.
A slightly different question may be to find out which pathways were used to express a certain observed phenotype.
Both types of problems can be conveniently addressed with our tools provided by TRANSFAC PATHWAYS package.
SBGN viewer:
- PathFinder is the web browser tool for visualization of signaling and metabolic pathways using (System Biology Graphic Notation) SBGN standard.
Upstream analysis:
The TRANSFAC PATHWAYS package uniquely combines promoter analysis with pathway analysis, enabling the identification of master regulators in gene regulatory networks. No other tool on the market provides such an integrated capability.
ODE modeling:
The TRANSFAC PATHWAYS package includes geneXplain platform modeling tools on the basis of BioUML simulation environment, which is according to the independent study (Maggioli F., Mancini T., Tronci E. SBML2Modelica: Integrating biochemical models within open-standard simulation ecosystems. Bioinformatics, 2019, doi: 10.1093/bioinformatics/btz860) shown as
TRANSFAC DISEASES
Identify drug targets and disease biomarkers
Introduction
TRANSFAC DISEASES comprises all data of TRANSFAC BASIC and TRANSFAC PATHWAYS plus The Human Proteome Survey Database (HumanPSD) which is a catalog of proteins and their complexes from human cells, plus their orthologs from mouse and rat sources.
Its main focus is on the association of human proteins with diseases as well as on their potential use as biomarkers.
TRANSFAC DISEASES allows to apply the full potential of the included gene regulation and disease data and tools. Particularly, TRANSFAC DISEASES includes Genome Enhancer – a fully automated pipeline for patient omics data analysis, which identifies prospective drug targets and corresponding treatments by reconstructing the molecular mechanism of the studied pathology.
Database content
(incl. all content of TRANSFAC BASIC and of TRANSFAC PATHWAYS)HumanPSD reports detailed information about the role of human proteins as biomarkers in diseases. Information can be retrieved on the molecular functions, biological roles, localization, and modifications of proteins, expression patterns across cells, tissues, organs, and tumors, consequences of gene mutations in mice, and the physical and regulatory interactions between proteins and genes.
Disease similarity by common biomarkers

Biomarkers:
HumanPSD reports over 140,000 gene-to-disease biomarker associations (causal, correlative, preventive, negative, prognostic).
Disease mechanism:
HumanPSD reports description of disease molecular mechanisms for over 3,900 human diseases.
Drugs and targets
HumanPSD reports over 55,000 drug targets and associated with them over 10,000 drugs.
Clinical trials:
HumanPSD reports over 1,100,00 clinical trial – disease connections extracted from ClinicalTrials.gov and AACT databases, and also from the registries and data partners contributions to the OpenTrials project.
Tools
(incl. all tools of TRANSFAC BASIC and of TRANSFAC PATHWAYS)Genome Enhancer

Welcome to the new era of Precision Medicine!
In addition to other TRANSFAC-, TRANSPATH- and HumanPSD-based tools, TRANSFAC DISEASES includes the AI driven Genome Enhancer, a fully automated pipeline for patient omics data analysis, which identifies prospective drug targets and corresponding treatments by reconstructing the molecular mechanism of the studied pathology.

Genome Enhancer provides a powerful synergism between the automatic pipeline for multi-omics data processing and the comprehensive bioinformatics toolbox of the geneXplain® platform integrated with the TRANSFAC, TRANSPATH, and HumanPSD databases.
Genome Enhancer offers:

Multi-omics analysis
Use genomics, transcriptomics, metabolomics, proteomics, and epigenomics data in one analysis run and receive an integrated report

Personalized medicine
Running the analysis on omics data of a certain patient, you will identify personalized prospective drug targets and corresponding treatments

Scientific base
Integration of promoter and enhancer analysis with pathway reconstruction gives unrivaled disease molecular mechanism modeling accuracy

Drug target identification
Genome Enhancer reconstructs a complex network of signal transduction pathways that are activated in the pathology and identifies their key regulators

Genome Enhancer Algorithm
Genome Enhancer uses Upstream Analysis, an integrated promoter and pathway analysis, to identify potential drug targets of the studied pathology.
Disease mechanism:
Genome Enhancer applies AI algorithms such as Genetic Algorithm and complex graph analysis algorithms to discover disease molecular mechanisms and
Multi-omics integration:
Genome Enhancer provides flexible integration of all five “-omics” data types: Transcriptomics, Genomics, Epigenomics, Proteomics, Metabolomics.
Drug repurposing:
Genome Enhancer can screen for existing FDA-approved drugs that interact with the disease-specific targets,
Detailed report:
Genome Enhancer delivers a comprehensive and detailed report that includes all the essential elements for publication-ready research.
TRANSFAC DOWNLOAD
Download TRANSFAC and do whatever you like
Introduction
TRANSFAC flat file download (including the databases TRANSCompel® and TRANSProTM) contains eukaryotic transcription factors (and miRNAs), their experimentally determined genomic binding sites and consensus DNA-binding motifs (PWMs), as well as data on combinatorial gene regulation and factor-factor interaction. Promoters, enhancers and silencers annotated with transcription factor ChIP-Seq, DNase hyper-sensitivity and histone methylated intervals from the ENCODE project and from other sources complement the manually curated binding site data.
Key features
- Intended for Bioinformaticians
- No installation is needed – just download and unzip archives
- Data files are provided in DAT and JSON formats
- Promoters are provided in the DAT and GTF formats
- Direct data access without user interface: data extraction is possible via Perl scripts or other programs written by the user
- Java-based tools for TFBS search (Match Library) are accessible via a command line
- For use with customer tools and incorporation into user-specific pipelines
What you will get
- Based on the positional weight matrices (PWMs) transcription factor binding sites can be predicted in regulatory regions.
- In the TRANSFAC® flat file download, the tools of the MatchTM Library can be used on command line or the PWMs can be used with tools of the user.
YOUR BENEFITS USING TRANSFAC 2.0
MOTIFS AND PREDICTION OF TF-BINDING SITES
Use the most comprehensive library of known eukaryotic transcription factor binding motifs
TRANSFAC systematically collects all available TF-binding motifs in the form of Positional Weight Matrices (PWMs) from scientific literature and repositories, as well as PWMs constructed by the TRANSFAC team on the basis of experimentally verified TF binding sites. Currently TRANSFAC provides more than 10,000 PWMs for various eukaryotic taxonomic groups. Our goal is to provide the most comprehensive resource of TF binding motifs for researchers world-wide
Identify common motifs in a set of target DNA sequences
Determine common motifs and compare these de-novo motifs to known transcription factor DNA binding site consensus sequences present in the TRANSFAC database
Detect genomic variants affecting TF-binding sites
Analyze mutations from your NGS data in regulatory regions for their potential negative or positive effect on transcription factor binding
Predict TF-binding sites in eukaryotic DNA sequences
Our tools predict transcription factor (TF) binding sites and composite regulatory regions using Machine Learning (ML) and Artificial Intelligence (AI)
PROMOTERS AND ENHANCERS
The unrivaled resource for studying promoters and enhancers
Due to its comprehensive data on transcription factors and their binding sites, tools for motif analysis, support for cross-species comparisons and functional annotations, TRANSFAC is an indispensable resource for studying promoters and enhancers
Find known transcriptional regulators for your gene(s) of interest
Search for factor-gene interactions in TRANSFAC, the largest collection of published experimentally proven transcription factor binding sites
Explore factor-factor interactions and composite elements
Complement the unparalleled collection of factor-gene interactions with factor-factor interactions and synergistic and antagonistic composite elements
Predict target genes
Find target genes for a transcription factor of interest by studying from single gene promoters to whole genomes
Analyze genes for tissue- and GO-specific transcription factors
Select tissue- / cell type- / induction-specific transcription factors for genes from human and model organisms
PATHWAYS AND MASTER REGULATORS
Identify pathways up- and down-stream of a gene (set)
Explore activation patterns of genes in tissues and cells of your interest and build complex interaction networks based on individual reactions with experimental details, protein-protein interactions (PPIs) and post-translational modifications (PTMs) in TRANSFAC PATHWAYS
Apply integrated network analysis and visualization
Profit from the combined approach towards causative gene regulation studies. Explore activation patterns of genes in tissues and cells of your interest and build complex interaction networks with identified master regulators
Map gene sets on pathways
Draw insights on biological function of your gene set by mapping them on pathways
Customize regulatory and metabolic networks
Build networks based on more than one million reactions extracted from original scientific literature and evaluated by experts.
MULTI-OMICS
Easily process and integrate all your omics data with TRANSFAC PATHWAYS / DISEASES
Preprocess, functionally explore, and unite various omics data (genomics, transcriptomics, metabolomics, proteomics and epigenomics) in a fully automized pipeline and get a combined and integrated report
Find common functional properties in a set of (co-regulated) genes
Map your data on various ontologies and identify overrepresented functional assignments in your gene set
Compare and functionally align your data
Observe how your omics data sets (genomics, transcriptomics, proteomics, epigenomics or metabolomics) correlate between each other
Utilize upstream analysis
Benefit from our unique upstream analysis approach combining promoter and pathway analysis to identify transcription factors and upstream master regulators (as potential drug targets) which can explain expression changes of your DEGs (or other changes in gene or protein signatures)
BIOMARKERS, DRUGS AND COMPOUNDS
Discover disease molecular mechanisms
Make use of the vast amount of gene-disease and gene-drug assignments and identify novel biomarkers and drug targets
Reconstruct disease molecular mechanism
Understand the drug’s mechanism of action (MoA) based on the collected omics data
Trace back the activated pathways
Detect disease master regulators, responsible for governing the pathology development processes, and therapeutic targets
PRECISION MEDICINE
Employ personalized medicine with TRANSFAC DISEASES
With our fully automated pipeline for patient’s multi-omics data analysis TRANSFAC DISEASES generates a comprehensive report about the personalized drug targets identified for a certain patient, or a group of patients, and the potentially effective drugs. Application examples include cancer, neurodegenerative diseases, infectious diseases, diabetes, metabolic diseases and hypertension
Develop a personalized therapy
Identify individual drug targets and corresponding treatments based on the pathology molecular mechanism reconstructed on omics data collected from a particular patient
Repurpose drugs
Explore how known drug targets can be activated in various pathologies. Check out the possible off-label usage of treatments and identify prospective drug combinations for better patient outcomes
Find new drug candidates
Identify novel drug targets and find prospective drug-like compounds potentially acting on them by using integrated promoter, pathway and cheminformatics analysis
GENERAL
Inbuilt workflows
Make use of over 200 pre-compiled workflows
Customizable pipelines
Construct your own dedicated analysis pipeline with visual programming
Integrated Genome Browser
Get your result in tabular format as well as in the integrated genome browser
Application Programming Interface (API)
Use Java-based API, R-based API or Jupiter notebook
Pathway/Network visualization
Visualize canonical pathways and analysis-dependent networks
Comprehensive analysis reports
Profit from automatically generated analysis reports including network visualizations, functional annotation diagrams and more
WHAT MAKES TRANSFAC 2.0 DIFFERENT FROM OTHER TOOLS?
- Most comprehensive database on gene regulation
TRANSFAC stands as the pioneering and most comprehensive database on eukaryotic transcription factors (TFs), their genomic binding sites (TFBS), and DNA binding profiles (PWMs).
- 35 years of curation and maintenance
Once established over 35 years ago, TRANSFAC has been diligently maintained and manually curated ever since.
- The biggest collection of experimentally proven functional TF binding sites
TRANSFAC 2.0 contains the biggest collection of experimentally proven TF binding sites that regulate expression of genes in genomes of eukaryotic organisms curated from original publications and documented with detailed information about tissue, cell types, TF source and quality of experimental evidence.
- The largest library of Positional Weight Matrices (PWMs)
TRANSFAC 2.0 contains over 10,000 DNA binding patterns in the format of positional weight matrices (PWMs) for animals, plants and fungi. PWMs are built based on experimentally proven TF binding sites, curated from original scientific publications and integrated from other databases.
- Signal transduction network of more than 1,200,000 reactions
TFs are connected to a network of more than 1,200,000 of signal transduction and metabolic reactions extracted from original scientific literature and evaluated by experts. Over 1500 canonical pathways are described based on these reactions.
- Unique algorithm to find master-regulators
Master-regulators are discovered by the “upstream analysis” that uniquely integrates promoter and network analysis using graph search and genetic algorithms.
- Biggest collection of more than 140,000 disease biomarkers
Manually curated collection of more than 140,000 gene to disease associations as correlative, causal and disease mechanisms biomarkers and drug targets.
- Reconstruction of disease molecular mechanisms based on the upstream analysis
Combining upstream analysis approach and disease and pathway information allows to reconstruct disease mechanisms and find novel drug targets.
- Over 300 powerful tools and pipelines to study gene regulation
TRANSFAC 2.0 provides a platform of multiple web tools and ready pipelines for analysis of NGS, RNA-seq, ChIP-seq, ATAC-seq, CUT&RUN and other types of genomics, transcriptomics, epigenomics, proteomics and metabolomics data. No cumbersome installation or special bioinformatics skills are needed.
- Robust AI algorithms for promoter and enhancer analysis
Integration of powerful tools for scanning genomes for TF binding sites and for discovering site enrichment and site combinatorial modules using AI, such as genetic algorithms, and machine learning.
- Automatic multi-omics discovery pipeline “Genome Enhancer”
Genome Enhancer provides a fully automated pipeline, including report, for patient omics data analysis, which identifies prospective drug targets and corresponding treatments by reconstructing the molecular mechanism of the studied pathology.
TRANSFAC versus JASPAR
Feature 9003241321086270_89d334-45> |
TRANSFAC 9003241321086270_4a90ed-5a> |
JASPAR 9003241321086270_f50187-43> |
---|---|---|
Database statistics 9003241321086270_e75479-23> |
Factors – 48,258 DNA Sites – 50,892 Factor-DNA Site Links – 68,900 Genes – 102,973 Matrices – 10,706 References – 45,130 9003241321086270_5f34f4-ee> |
– No DNA Sites -2,000 profiles (Matrices) in JASPAR core (2024 release) 9003241321086270_9940af-1f> |
Database statistics (miRNA) 9003241321086270_b3a718-ea> |
miRNAs – 1,772 mRNA Sites- 67,703 miRNA-mRNA Site Links – 74,553 9003241321086270_89f830-b7> |
No miRNA data 9003241321086270_828793-10> |
Database statistics |
Distinct transcription factors in Chip-seq experiment : 1,171 TF-TG associations : 15,639,406 ChIP TFBS : 95,867,624 9003241321086270_2ddfb6-29> |
No Chip-seq data. 9003241321086270_06526f-2c> |
Data Depth 9003241321086270_6f32b4-37> |
Genome annotation of experimentally validated TF binding sites Genome annotation of enhancers, genome conserved regions. 9003241321086270_d6b83b-c5> |
Limited to binding motifs 9003241321086270_ec152c-1a> |
Data Quality 9003241321086270_c64096-9c> |
Combines public and proprietary datasets, enhancing dataset completeness. 9003241321086270_437011-d0> |
Restricted only to open-access data. 9003241321086270_23d605-39> |
Data Integration 9003241321086270_be11b3-12> |
Links TF binding site data with additional omics data, including epigenetic modifications and expression profiles. Supports multi-layered analyses that combine DNA-protein interactions and gene expression. 9003241321086270_64e843-72> |
Focuses on TF motifs and provides limited integration with other datasets. 9003241321086270_030569-e7> |
Integrated Pathway Analysis 9003241321086270_1a3cef-83> |
Supports integrated promoter and pathway analysis allowing to identify Master Regulators of the studied processes, which in their turn can serve as prospective disease mechanism-based biomarkers and drug targets 9003241321086270_8458bd-65> |
Limited exclusively to promoter analysis with no further pathway analysis extensions supported 9003241321086270_43b733-3b> |
Additional tools 9003241321086270_711ae6-48> |
Offers tools like MATCH™ for TFBS prediction and analysis., Click and Run pipelines integrating TRANSFAC for identifying enriched binding sites, composite modules, combinatorial analysis 9003241321086270_cd2c62-63> |
No own tools. Linked to third-party tools for motif scanning and sequence analysis 9003241321086270_224634-aa> |
AI-based extensions 9003241321086270_b43700-8b> |
Includes AI and ML based methods for prediction of TFBS combinations, including construction of composite modules based on a genetic 9003241321086270_a41bb9-cb> |
Limited to standard approached towards motif scanning and sequence analysis 9003241321086270_027817-b3> |
Clinical Relevance 9003241321086270_fd6b74-62> |
Annotated for disease-related transcription factors and binding sites. In addition to biomarker info, includes annotations for drug-disease-clinical trials relations 9003241321086270_bf3322-d0> |
Minimal disease annotations 9003241321086270_f28127-18> |
Species 9003241321086270_75eb97-5c> |
Includes data on multiple species of vertebrates, nematodes, yeast, insects, plants. TRANSFAC is integrated with geneXplain platform and provides flexibility to integrate new custom genomes and identify transcription factor binding sites 9003241321086270_d865d7-a8> |
Includes TF binding motifs for six organism classes. Integration of new custom genomes is not provided 9003241321086270_35e2ee-23> |
Customer Support 9003241321086270_5d6a03-f4> |
Regular updates, Prompt customer support with technical assistance by experts in the industry 9003241321086270_f39b09-0c> |
Open-source platform, assistance through documentation 9003241321086270_f9d0a5-18> |
Accessibility 9003241321086270_69c93c-fd> |
Flexible, affordable and customized packages available to access total TRANSFAC functionality 9003241321086270_400545-cf> |
Freely accessible for academic and non-commercial research 9003241321086270_b3b9ba-7f> |
Selection of articles reporting about HumanPSD applications:
- Kawashima Y., Nagai H., Konno R., Ishikawa M., Nakajima D., Sato H., Nakamura R., Furuyashiki T., Ohara O. (2022) Single-Shot 10K Proteome Approach: Over 10,000 Protein Identifications by Data-Independent Acquisition-Based Single-Shot Proteomics with Ion Mobility Spectrometry. J Proteome Res. 21(6), 1418–1427. Link
- Lim, J. S., Ibaseta, A., Fischer, M. M., Cancilla, B., O’Young, G., Cristea, S., Luca, V. C., Yang, D., Jahchan, N. S., Hamard, C., Antoine, M., Wislez, M., Kong, C., Cain, J., Liu, Y. W., Kapoun, A. M., Garcia, K. C., Hoey, T., Murriel, C. L., & Sage, J. (2017). Intratumoural heterogeneity generated by Notch signalling promotes small-cell lung cancer. Nature, 545(7654), 360–364. Link
- Reales‐Calderón, J. A., Aguilera‐Montilla, N., Corbí, Á. L., Molero, G., & Gil, C. (2014). Proteomic characterization of human proinflammatory M1 and anti‐inflammatory M2 macrophages and their response to Candida albicans. Proteomics, 14(12), 1503-1518. Link
- Martínez‐Solano, L., Nombela, C., Molero, G., & Gil, C. (2006). Differential protein expression of murine macrophages upon interaction with Candida albicans. Proteomics, 6(S1), S133-S144. Link
Publications
Selection of publications authored by the geneXplain team:
- Kisakol, B., Matveeva, A., Salvucci, M., Kel, A., McDonough, E., Ginty, F., Longley, D., Prehn, J. (2024) Identification of unique rectal cancer-specific subtypes. Br J Cancer. DOI https://doi.org/10.1038/s41416-024-02656-0. Link
- Kolpakov, F., Akberdin, I., Kiselev, I., Kolmykov, S., Kondrakhin, Y., Kulyashov, M., Kutumova, E., Pintus, S., Ryabova, A., Sharipov, R., Yevshin, I., Zhatchenko, S., & Kel, A. (2022). BioUML-towards a universal research platform. Nucleic Acids Res. 50(W1),W124–31. Link
- Orekhov A.N., Sukhorukov V.N., Nikiforov N.G., Kubekina M.V., Sobenin I.A., Foxx K.K., Pintus S., Stegmaier P., Stelmashenko D., Kel A., Poznyak A.V., Wu W.K., Kasianov A.S., Makeev V.Y., Manabe I., Oishi Y. (2020) Signaling Pathways Potentially Responsible for Foam Cell Formation: Cholesterol Accumulation or Inflammatory Response-What is First? Int J Mol Sci. 21(8),2716. Link
- Kel A., Boyarskikh U., Stegmaier P., Leskov L.S., Sokolov A.V., Yevshin I., Mandrik N., Stelmashenko D., Koschmann J., Kel-Margoulis O., Krull M., Martínez-Cardús A., Moran S., Esteller M., Kolpakov F., Filipenko M., Wingender E. (2019) Walking pathways with positive feedback loops reveal DNA methylation biomarkers of colorectal cancer. BMC Bioinformatics. 20(Suppl 4),119. Link
- Boyarskikh, U., Pintus, S., Mandrik, N., Stelmashenko, D., Kiselev, I., Evshin, I., Sharipov, R., Stegmaier, P., Kolpakov, F., Filipenko, M., Kel, A. (2018) Computational master-regulator search reveals mTOR and PI3K pathways responsible for low sensitivity of NCI-H292 and A427 lung cancer cell lines to cytotoxic action of p53 activator Nutlin-3. BMC Med. Genomics 11(Suppl 1), 12. Link
- Kel, A.E., Stegmaier, P., Valeev, T., Koschmann, J., Poroikov, V., Kel-Margoulis, O.V. and Wingender, E. (2016) Multi-omics “upstream analysis” of regulatory genomic regions helps identifying targets against methotrexate resistance of colon cancer. EuPA Open Proteomics 13, 1-13. Link