CLDN18 and cancer: The alveolar signature we detected in the cancer cells at RD includes both AT1- and AT2-associated genes (Table S2), including AQP4, SFTPB/C/D, CLDN18, FOXA2, NKX2-1, and PGC for AT2 cells (Desai et al., 2014; Liu et al., 2003; Nabhan et al., 2018; Wade et al., 2006; Xu et al., 2016; Zhou et al., 2018) and AGER, HOPX, and IGFBP2 for AT1 cells (Nabhan et al., 2018; Serveaux-Dancer et al., 2019; Figure S3B).