KRT5 and pulmonary fibrosis: Differentiation of AT2s is key for regeneration in injured alveoli marked by their expression of transient basaloid features such as Keratin 5 (KRT5) and the amount of alveolar KRT5+ basaloid cells directly correlates with disease progression in pulmonary fibrosis (29, 37, 38), mirrored by the decreased expression observed in our study.