To further explore whether transitional cells promote fibrosis and whether keratins play a functional role in the accumulation of transitional cells and fibrogenesis, we interrogated a meta-analysis of 5 human IPF GWAS studies (74) for variants in the keratin genes highly expressed by transitional AECs: KRT7, KRT8, KRT17, KRT18, and KRT19. Here, KRT18 is linked to idiopathic pulmonary fibrosis.