KRT5 and idiopathic pulmonary fibrosis: It is also shown that in the foci of fibrosis in patients with idiopathic pulmonary fibrosis, the number of these cells is significantly increased [44], and that this cell population is able to transdifferentiate into keratin-5-positive basal cells (CK5+) with subsequent differentiation into bronchial epithelium, which may explain the phenomenon of bronchialization of alveoli in idiopathic pulmonary fibrosis [45].