Researchers from the Broad Institute of MIT and Harvard have shown that a CRISPR-based editing system can cut and bind RNA in mammalian cells. In a paper out this week in Nature, the team used CRISPR-Cas13, which the researchers had helped discover, to both reduce RNA levels and “tag” RNAs in order to view and track them within cells. The researchers previously used CRISPR-Cas13 to target RNA in bacterial cells, but proving that the system could work safely and effectively in mammalian cells was a critical step toward using the system to study human biology and disease.