Reporting in the journal Science Translational Medicine, scientists say two different so-called growth factors—naturally occurring substances that stimulate cell proliferation—activate in the airways of severe asthma patients as they inhale corticosteroids used as an emergency treatment during an asthma attack. The discovery was made as researchers investigated an enduring mystery in asthma treatment: Why do some patients who suffer the most from the disease often have the least success with conventional rescue treatments? To read the full story.