By single-cell RNA sequencing analysis, the subpopulation with high C-X-C motif chemokine ligand 12 (Cxcl12) expression and low nitric oxide synthase 3 (Nos3) expression showed a pro-fibrotic phenotype that was enriched in biological processes related to lung injury and fibrosis, suggesting its role in recruiting monocytes, inducing fibroblast proliferation, and promoting the ECM, and may play a key role in pulmonary fibrosis through potential cross-linking with AMs and stromal cells [11]. The gene discussed is NOS3; the disease is pulmonary fibrosis.