Our data, in consensus with the existing literature, suggested an increase in basal and aberrant basaloid cells in the distal lung epithelium of IPF patients, which have, in the past, been identified by their intracellular expression of cytokeratin 5 (CK5, the protein product of KRT5 mRNA) or cell surface expression of NGFR [47,48]. Here, NGFR is linked to idiopathic pulmonary fibrosis.