In the lab, new molecular on/off controls helped tame a toxic cancer drug and sped up a coronavirus diagnostic test by more than 70-fold. In a recent study, a new way to potentially control when drugs are active or inactive in the body has been introduced. To address this concern, a team from the Baker Lab used computers to create custom proteins that latch onto target molecules. In the study, a switch introduced into a light-emitting enzyme yielded a bright signal that could be toggled in seconds. The same approach might be used to create rapid sensors for disease markers, environmental pollutants and other chemicals.