Mice lacking periostin respond to lung antigen challenge with significantly decreased number of eosinophils in the lung and have reduced allergic skin inflammation (Blanchard et al., 2008; Bentley et al., 2012; Masuoka et al., 2012), thus implicating periostin as a ligand in eosinophil recruitment and retention in allergy and asthma. The gene discussed is POSTN; the disease is asthma.