Researchers discovered humble mitochondria are sometimes boss over the cell nucleus. They send DNA-coded instructions to make the nucleus respond when the cell is under duress. That’s new, as the nucleus was always thought to issue orders to cell members. The breakthrough helps explain intracellular communication, as communication breakdown leads to human diseases such as cancer and Alzheimer’s. The findings also open a new pathway for treatments that can address both genomes — in the nucleus and the mitochondria.