It has previously been demonstrated with single cell RNA sequencing a subpopulation of cells that expressed features of both AEC2 and AEC1 cells in both control and IPF lungs40,43, where Habermann et al. at gene level identified novel epithelial cell phenotypes, including a KRT5−/KRT17+ ECM-producing epithelial cell population in the lungs obtained from patients with pulmonary fibrosis40. The gene discussed is KRT5; the disease is idiopathic pulmonary fibrosis.