bookmark VIPER / Virtual Inference of Protein activity by Enriched Regulon analysis Evaluates protein activity. VIPER can transform low-depth single cell RNA-Seq (scRNA-Seq) profiles into highly reproducible protein activity profiles. It underlines cell state and allows users to delete technical artifacts and batch effects. This tool permits investigation of critical lineage markers and can serve to deduce differential protein activity. It is useful for the analysis of single cell biology.