In addition, we observed positive co-staining of ACE2, TMPRSS2, or NRP-1 with α-tubulin+ ciliated and MUC5AC + goblet cells in tracheobronchial ALI tissues (Fig. 1a), and SP-B+ cells in alveolar ALI tissues (Fig. 1b). Here, SFTPB is linked to acute respiratory distress syndrome.