Scientists in China have developed a probe that could be used to test how well a patient will respond to certain drug treatments. The new probe measures the activity of N-acetyltransferase 2 (NAT2), an enzyme that metabolises drugs and other toxins containing aryl amines and hydrazines. The activity of NAT2 differs between individuals, which affects how well a drug will work, and dysfunction of the enzyme has been linked to breast cancer, Parkinson's and other diseases. A simple measure of NAT2 activity could help ensure patients are given drugs that they can metabolise effectively with minimal side effects. Xuhong Qian and colleagues...