In plants and nematodes, short RNA sequences also act like hormones, carrying messages between cells. Now, a $17 million research program in research grants, announced this month by the U.S. National Institutes of Health, aims to determine whether extracellular RNA (exRNA) has a similar communication role in people—and whether it can be harnessed for diagnosis and treatment of human diseases. In humans and other mammals, exRNAs abound in blood, tears, saliva, and every other body fluid, but definitive data that such exRNAs influence recipient cells have been missing. Some of the 24 newly funded projects will assess whether exRNAs can serve as biomarkers—molecular indicators that help doctors diagnose illnesses or identify which people are susceptible. Other projects will investigate whether exRNAs can help fight diseases such as cancer, Huntington's disease, and multiple sclerosis.