PLAU and pneumonia: We first addressed the role of uPA and uPAR in COVID-19-induced lung fibrosis through data-mining of scRNA-seq datasets from (i) warm postmortem lung biopsies of patients diseased from COVID-19-associated pneumonia and lung fibrosis, (ii) lung biopsies from individuals with pulmonary fibrosis (PF) and (iii) control samples (control) from healthy donors reported in Habermann et al. and Bharat et al. (GSE158127, GSE135893 [35,36]).