MicroRNAs help to control which proteins are generated in cells by reducing the stability and translation of specific messenger RNAs. Because of their importance in regulating gene expression, a different set of microRNAs is expressed in each cell type, and the abundance of each microRNA is tightly controlled by its rates of generation and destruction. Writing in Nature, Farnung et al.1 detail a pervasive mechanism for this destruction. Access Nature and 54 other Nature Portfolio journals Get Nature+, our best-value online-access subscription $32.99 / 30 days cancel any time Subscribe to this journal Receive 51 print issues and online access $199.00 per year only $3.90 per issue Rent or buy this article Prices vary by article type from$1.95 to$39.95 Prices may be subject to local taxes which are calculated during checkout doi: https://doi.org/10.1038/d41586-026-00632-7 Farnung, J. et al. Nature https://doi.org/10.1038/s41586-026-10232-0 (2026). Article Google Scholar Ameres, S. L. et al.…