IL4 and idiopathic pulmonary fibrosis: A recent study showed that treatment with IPF-relevant cytokine cocktail (including IL-1β, TGF-β1, TNF-α, IL-8, IL-33, IL-13, IL-4, TSLP, and MCP-1) altered the differentiation direction of alveolar and small airway epithelial stem cells (Schruf et al., 2020).