Recently, Stancil et al. (2021) have demonstrated that one copy (GT) of MUC5B promoter variant prolonged the persistence of amphiregulin-induced unjammed phase in IPF-derived airway epithelial cells as compared to the no copy (GG) variant, while epithelial cells with this unjammed phase promoted proliferation and activation of human lung fibroblasts. Here, MUC5B is linked to idiopathic pulmonary fibrosis.