Chronic asthma often results in scarring of the lung airways (airway fibrosis) and this can cause airway obstruction. The soluble factor TGF-beta-1, produced by inflammatory cells known as eosinophils, has been shown to drive the processes that result in airway fibrosis, notably fibroblast proliferation and extracellular matrix deposition. Now, James Malter and colleagues at the University of Wisconsin School of Medicine and Public Health, Madison, have generated new data in rodents that has led them to suggest that targeting the protein PIN1 might provide a new approach to limiting airway fibrosis driven by the production of TGF-beta-1 by activated eosinophils in individuals with chronic asthma.