ACE2 and pulmonary fibrosis: We explored five publicly available single-cell respiratory system tissue transcriptome datasets (GSE122960, GSE124872, GSE127465, GSE131391, and Adams dataset which is only available for interactive viewing) that focused on different conditions, including idiopathic pulmonary fibrosis (IPF), aging lungs (mouse origin data), lung cancers, and smoked branchial epithelium, for specifically reanalyzing the ACE2 and TMPRSS2 expression profiles (Adams et al., 2019; Angelidis et al., 2019; Duclos et al., 2019; Reyfman et al., 2019; Zilionis et al., 2019).