Single-cell RNA sequencing of lung cancer tissues revealed that some AT II-associated genes expressed differently in the lung cancer cells, including aquaporin 4 (AQP4), surfactant pulmonary associated protein B (SFTPB), surfactant pulmonary associated protein C (SFTPC), surfactant pulmonary associated protein D (SFTPD), claudin 18 (CLDN18), forkhead box A2 (FOXA2), NKX homeobox-1 gene (NKX2-1), and pepsinogen C (PGC) [24]. This evidence concerns the gene CLDN18 and lung carcinoma.