miRDB is an online database designed for predicting functional microRNA (miRNA) targets and their functional annotations. The authors have recently updated miRDB with an improved algorithm, MirTarget, which has significantly enhanced the accuracy of miRNA target prediction. The updated database now includes 3.5 million predicted targets regulated by 7000 miRNAs across five species (human, mouse, rat, dog, and chicken). Key features of the updated miRDB include: 1. **Updated Target Prediction Data**: The new algorithm, MirTarget, integrates miRNA binding and target expression data to predict miRNA targets more accurately. The database now supports transcriptome-wide predictions for five species, with a significant increase in the number of predicted targets compared to the previous version. 2. **Custom Target Prediction**: Users can input custom miRNA or gene target sequences to predict potential targets or regulators in one of the five species. The web server provides a flexible interface for custom predictions, allowing users to review detailed prediction results. 3. **Cell-Specific Target Prediction**: miRDB now offers prediction data tailored for specific cell models, integrating over 1000 cell line expression profiles. This feature helps researchers identify cell-specific miRNA targets for further experimental validation. 4. **Target Ontology Analysis**: A new web interface allows users to integrate target prediction data with Gene Ontology (GO) annotations to predict miRNA functions. This integration provides a streamlined pipeline for inferring biological pathways regulated by miRNAs. All data in miRDB are freely accessible at http://mirdb.org. The updates aim to facilitate the identification of miRNA functions and targets in various experimental systems, enhancing the utility of the database for researchers in the field of miRNA research.miRDB is an online database designed for predicting functional microRNA (miRNA) targets and their functional annotations. The authors have recently updated miRDB with an improved algorithm, MirTarget, which has significantly enhanced the accuracy of miRNA target prediction. The updated database now includes 3.5 million predicted targets regulated by 7000 miRNAs across five species (human, mouse, rat, dog, and chicken). Key features of the updated miRDB include: 1. **Updated Target Prediction Data**: The new algorithm, MirTarget, integrates miRNA binding and target expression data to predict miRNA targets more accurately. The database now supports transcriptome-wide predictions for five species, with a significant increase in the number of predicted targets compared to the previous version. 2. **Custom Target Prediction**: Users can input custom miRNA or gene target sequences to predict potential targets or regulators in one of the five species. The web server provides a flexible interface for custom predictions, allowing users to review detailed prediction results. 3. **Cell-Specific Target Prediction**: miRDB now offers prediction data tailored for specific cell models, integrating over 1000 cell line expression profiles. This feature helps researchers identify cell-specific miRNA targets for further experimental validation. 4. **Target Ontology Analysis**: A new web interface allows users to integrate target prediction data with Gene Ontology (GO) annotations to predict miRNA functions. This integration provides a streamlined pipeline for inferring biological pathways regulated by miRNAs. All data in miRDB are freely accessible at http://mirdb.org. The updates aim to facilitate the identification of miRNA functions and targets in various experimental systems, enhancing the utility of the database for researchers in the field of miRNA research.