Shortly after, using immunofluorescence studies, Smirnova et al. quantified KRT5+ and KRT14+ basal cell population in healthy and IPF lungs and equally observed a drastic increase of basal cell populations in the distal IPF lung and proposed KRT14+ as a marker for an aberrantly differentiating progenitor cell pool [25]. Here, KRT5 is linked to idiopathic pulmonary fibrosis.