Nintedanib significantly reduced the infiltration of immune cells (including mast cells [MCs] and eosinophils) and neutrophils (147), but not that of macrophages, inhibited granuloma formation (148), and decreased the levels of other proinflammatory cytokines, including IL-4, IL-5, IL-6, and IL-13 (149), during lung fibrosis. The gene discussed is IL4; the disease is pulmonary fibrosis.